Same here man, I'm always tight on cash and never really have a lot of time on my hands, so I find myself buying fast food more often than I should, and I think it's finally starting to catch up with me. The thing is, when i get fast food I don't even eat that much of it, maybe just one burger and some fries, but after a while it still adds up. I'm starting to get a belly and my 32 waist pants are getting harder to squeeze on everyday, so I might have to move up to a 33 or 34 waist. Also, my face is noticeably rounder now.

I used to eat junk food all the time as a kid and throughout my teen years (and I mean A LOT, like, to the point where I'm surprised I didn't get diabetes) and I wouldn't gain a pound, but I think now my metabolism is finally starting to slow down and catch up with me. I wish eating healthy was more convenient and cheaper. I mean, eating healthy can be cheap if you look in the right places, but it will never be cheaper than fast food/junk food.

Spot on, I mean you spend E5 or whatever it is for a Big Mac meal and yet you're hungry, lethargic and bloated 30 minutes later, can't do that at all.    Cooking and preparing as much food as possible from fresh and it will save you a ton of cash, along with being infinitely healthier & tastier than any ready meals & fast food.  With a tiny amount of thought and effort, it's way, way easier to eat healthy than most would think.  Best way to start is to start cooking yourself and get stuck into couscous, tabouleh, falafels, salads, wraps, as much wholegrains and brightly coloured fruit & veg as possible, avoid beige/white food like white bread and anything processed or deep-fried.   

This breakfast smoothie works for me -
200ml apple juice, 1 carrott, 1 banana, small slice of root ginger, fresh pineapple, 1 mandarin, add a couple of spoonfuls of muesli & mixed seeds (pumpkin, sunflower, linseed, hemp) for texture.  I generally eat that with a small bowl of muesli, pineapple/banana & greek yoghurt or poached eggs & tomato on wholegrain or rye bread followed soon after with a double espresso & I'm raring to go for the day - no post-meal slump or food coma.

In general -
Try making your own pizza, it's really simple and you'll never, ever go back to frozen supermarket shit or whatever crap gets dished out at Dominos or Pizza Hut.
Sushi takes a while to prepare the rice, but you can make a fuckload of it and keep it going for a few days.  It's ridiculously cheap to make too.
Swap wholegrain pasta for the standard beige crap, you'll notice you've got more energy and are more alert afterwards.
Grow some rocket, coriander & basil in your kitchen.  The smell alone will inspire you to cook more and they always add awesomeness to any dinner.
Spaghetti or linguine served with fresh prawns, garlic, rocket, lemon & cherry tomatoes with a little parmesan, pepper & chilli to taste can take less than 10 minutes to prepare, serve & cook.  Super easy, cheap & tasty as all hell.
Eat lots of little meals during the day, mainly fresh fruit along with some nuts & seeds, washed down with water & you're doing your metabolism a massive favour.  Coke, Sprite, etc. are filth, just avoid them, unless mixed with JD or vodka or similar.