Hey Areyanna,
I am T1 but also a personal trainer. To make your bum bigger you need to target that specific area. To target your glutes you need Squats and lunges, either with your own body weight which will tone your bum,or with dumbells for added weight - which will slowly build the muscle and give your bum a sexy rounded shape. The heavier the weight the more glucose you will use up in a short space of time so keep a close eye on your sugars. Incorporate this into your usual cardio workout if you have one, if you dont they can be done alone but you will get better results with an all over body workout!! (get onto to youtube for some great videos and tips on how to do the perfects squats/lunges)
Charlye