ok everyone i know its a small tank and i'm sorry, but i think everyone's being a little harsh on me, including when someone said that the seller should have never sold them to me:[
this was definitely the reason why i was a little hesitant on even taking a picture of my tank:[
i am indeed a first time fish owner, and i only researched bettas because thats the purpose of this tank.
sadly, whenever i ask my mom to just by me more fish flakes and etc, she buys these new fish on a whim thinking my betta will get lonely.
i am trying to pry off a 10-15 gallon tank from my friend, since he and his family arent even using it.
i think everyone makes mistakes in the beginning but you guys shouldn't attack them:[
OK. I think you're feeling a bit attacked, and I promise that is not how it is intended. Members on here are very passionate about fish wellbeing and can sometimes come off a little intense when someone has fish in what we consider to be the wrong tank circumstances.
Why don't you buy your own fish flakes from now on? That way you can sure she won't be in the store and tempted to buy another inappropriate fish.
Also, call the store and explain the situation to them. It is very likely that, when you explain that these fish have been forced upon you when you didn't really want them or have appropriate housing for them, that they will take them back and either refund you, or, more likely give you some credit for other things (decor, plants, food etc). Then you can get back to your original plan. If she buys another fish for your tank that is not suitable, take it back to the shop immediately.
Finally, you're 17, I think you're old enough to be able to explain to your mum that it is not acceptable for her to buy you fish out of the blue. I know those kinds of conversation are awkward to have, espcially with someone who wants you to be happy and realises that fish will do that, and who doesn't understand that not all fish are the same and have the same requirements, but it's for the wellbeing of the fish, and that should be paramount when you're a fishkeeper.
As a method of meeting her midway, you could tell her that, if she really doesn't want the betta to get lonely, then it'd be alright for her to buy you an apple snail or a couple of shrimp. Then go in to the store with her on a weekend and choose one out together and let her pay. That way she feels she's contributed and the fish won't get lonely, and you've got a suitable companion for your betta rather than a tank full of mismatched fish