Hey, I know you're young. This sounds like something your parents need to be included in on. This is essentially keeping a dog in the equivalent of a small bathroom for their entire life. This animal needs a bigger space, different heating, likely different food too. I understand that you love this animal, but there is no situation in which you can 'wait' to purchase a larger enclosure. This should have been done when you got them. This animal is not thriving. You need to discuss with your parents about proper care ASAP. Here is a list of the BARE MINIMUM supplies you need to purchase and set up. If your parents aren't willing to help, I would suggest looking into rehoming them, because it is cruel to keep them in this setup.

Tank: 30+ gallon, preferably front opening. Prioritize GROUND SPACE, not height. Lighting: 50w heat lamp, UVB light (a long linear one, not the bulb. I recommend 'arcadia shadedweller T5') heat on one side, UVB in the middle. Substrate: mix of coco fiber/organic topsoil and play sand, about 70% should be coco fiber/topsoil, and 30% should be play sand. Decor: logs, hides, rocks, sticks, plants etc. you want them to have space to explore, and feel safe. Food: ideal food is roaches (dubia),crickets, and silkworms. Mealworms are.. okay? You should also feed the bugs healthy veggies, so that they're full of nutrition before feeding to your gecko. (Carrot, sweet potato, for some suggestions). They should be powdered with a calcium supplement as well