One more thing...

I don't always do the cheesy conventional thing, but my gosh I suddenly desperately want to write a blog post in the form of a letter to teenage me – baby Gracie, chewing on her thumbnails during a particularly challenging GCSE exam, dyeing her hair dark brown/purple every week, sitting under the shelter at break time bearing down on a packed lunch of peanut butter sandwiches and pots of chickpeas while pondering the problematic relationship between Liam and Naomi in 90210. She needs a little guidance at times, and I feel it's my duty to help her out. 
Follow these steps, my dear, and you'll be right as rain. 

If you're going to wear eyeliner to school, be subtle and even it out.
I'd sneak off to the girls' toilets between lessons to top up my thick layer of No7 brown pencil eyeliner – only beneath my eyes, though. I'd never dare draw any on my eyelid, above my lashes, no way. Only the scene girls did that while walking home; they'd swap shoes and put their chequerboard Vans on, let their extensions down from the side-ponytails then slick some black liquid all around their eyes. I didn't want to step on their toes, or try to be part of their super-cool clique. Oh also Gracie, make sure you don't rub your eyes vigorously in Music lessons despite how deathly boring your teacher is – you'll turn into a panda.

It's okay to not be a whizz at everything.
Time and time again I'd skip merrily out of English class and into Art Textiles, good grades not far away and feeling genuine comfort in lessons chatting to teachers and putting my hand up to offer opinions. Then suddenly I'd find myself marching reluctantly to Maths and Science, hiding away in the corner and doodling all over my book covers rather than doing boring confusing calculations. I'd worry I was stupid, that it was wrong to be perfectly proficient in some subjects and appalling in others, that you're either a good student or a brain dead back-row rebel. No, honey. You have strengths and weaknesses. Someday your strengths will be the only thing you study, and you'll have the best time, but for now you have to nod along when Miss Mant explains Pythagoras to you for the millionth time.

You CAN have a varied taste in music.
Your best friend plays Release by Timbaland (ft JT) on her iPod during Maths, you have a headphone each, and you just wanna pop and lock all over the place. You listen to the one and only Taylor Swift Fearless album while walking home. Sometimes when feeling especially agro and angsty, Bowling For Soup are the way to go. When sad or reflective, only Kelly Clarkson will do. City & Colour speaks to you on every level.
Actually, I'm very grateful to the pop-punk lover boys I once fancied – I have the best taste in music thanks to them. I'd hear them talking about their favourite bands, or friends of theirs would send me mp4 files of their favourite songs, then I'd make a point of listening to them loudly while I waited near these boys to go into a classroom – I always hoped my headphones would leak and they'd turn around to say 'Hey, I love that song!' I hadn't seen the film yet, and wouldn't for the four years until it was released, but I always wanted a (500) Days of Summer moment. So yes, I discovered my all-time favourite bands because back in the day I'd wanted to snog the mop-heads in set 1.

She's not your friend.
Stop trying to fit in with people who don't give a flying f-word about you. Sure, you'd run across town to their house in a heartbeat if they texted simply saying 'idk bit sad rn :'( xxXxxXxx' but would they do the same for you? You know what she says behind your back, but she's perfectly nice to your face so you focus on that. Even when she embarrasses you in front of her 'popular' friends, you brush it off and giggle with them, then cry a little too hard when chopping onions in a Food Tech double.

You'll know when you're in love.
Don't force yourself to feel things for someone just because they say they feel them for you... Y'know? He may buy you Oreos, burn you the odd CD and cuddle you when you need it, sure. You love the sweet gestures and closeness, but you don't love him. You shouldn't feel bad about that, though! Arghh, it's hard to explain sweetie, but you'll get there someday. A guy will hang out with you every day, watch TV with you, buy you king size bars of Bournville, quote shows you watch and be absolutely word-perfect – do all the nice gestures you've experienced aged sixteen, but this time it'll be different. You'll be so full of this alien amorous amazing sensation, brimming fit to burst, and wanting to talk and write about it all day every day – rather than just at sleepovers with friends who are so totes in luv with their playground boyfs and you play along. When it's love, you'll know it. I promise.

Love your body. Now.
You envy the popular girls who have the coveted thigh gaps and perfect pert butts, and at times you hate the thin yet inexplicably buxom girls who are getting a ton of attention when they bounce impressively with every step down the corridor. Don't stuff your bra. Don't wear flat unsupported shoes just so you don't seem awkwardly tall, your back will kill as a result. Don't spend loads of your parents' money getting a trendy Toni & Guy haircut that doesn't suit you. Don't hide in the shower cubicles when getting changed for PE, be brave and stand among your peers who are no doubt just as concerned about their thighs and tummies as you are, they just choose not to let it get to them as much. Your body changes so so much over the next few years, and at twenty-one it still isn't settling down. You have to allow it to change, and accept that everyone has a different shape for goodness' sake – you have a tiny waist and a big butt. That ain't gonna change if you skip your dinner every other night. Be content with yourself.

There are a million more pointers I could give to that young'un, but I think these are the most key. I could go on and on about how frequent spot breakouts are normal, how thinking certain girls are pretty does not make you a lesbian, how it's important not to be embarrassed to ask to go to the loo during a lesson, how reading fiction books beneath the textbooks in Science doesn't make you a geek but isn't great for exam prep, how plucking your own eyebrows is both playing a dangerous game and fighting a losing battle... No, that's it.

https://www.youtube.com/watch?v=r6OuvaesBB0 – One of my all-time favourite songs that came into my life via a skateboarding freckled mop-head classmate that I totally wanted to walk to and from school with. Cheers, mate. That new haircut looks good.