I am using a game engine that only export to android (i dont have a pc so i develop games using mobile.)

I just wanted to ask if its okay to upload android only games

I'm not that sure if android only games are allowed, I think you should have a PC/Mac/Linux/Web port too, but I can't say anything 100% for sure. You should borrow your friend's or neighbor's PC/laptop during the jam, and return after the jam is over, or if you're under 18, ask your parents to borrow their PC/laptop

Our judges may not have access to an android phone (I personally don't either). I would highly recommend finding a way to port your game to a more accessible platform like web or PC. Your game wouldn't be removed from the jam, as long as it follows all other rules, but it would probably not make it through judging. 

Technically, Android apps can be easily run through https://www.bluestacks.com/ru/index.html on PC (and, probably, on MAC, I think). You can find someone with PC to test your Android build this way) Just an idea.