I bred dwarf gouramis when I was about thirteen or fourteen. I did it in a ten gallon. Bit different than bettas but same concept. First egglayers I bred. Now im almost fifty and I've had aquariums my whole life, and my kids are starting their own breeding projects with fish. Sorry to get nostalgic but you can have a blast raising fish at your age, and you can do it on a tight budget. I used to use Tupperware to raise the fry and did frequent water changes if I couldn't afford filtration.
Anyways, best of luck and have fun!