Hi Nat, look what you've done now. Caused a bloomin fight.
You are very slim and you might have to get a made to measure suit. The most important things about a budget drysuit for the type of diving you are doing is that they FIT and they don't leak.
They are a massively expensive piece of kit.
I agonised for 18 months before buying one. I ended up getting a MTM from Gryphon
Gryphon Watersports Online
I've never met anyone else on YD who has had a suit from them. So maybe they aren't every one's cup of tea. But they will custom build your suit to your exact specifications, boots, valves, wrist/neck seals, colour, material (quite a few different types of laminate to choose from). They are very helpful.
If you belong to a club, can you ask to borrow different types and try them in the pool? That will give you a bit of a feel for them.
Sometimes, dive shops have second hand ones for sale. You could buy a cheap one and get it altered to fit. ( I know you are a student and therefore poor!)
It's a big purchase and a tough choice to get it right.
But you might not want to listen to me cos my suit is orange and makes me a laughing stock on YD! Still, the students love it because they can see me.