Which form of Birth Control should i use Please Help?

Hi, im 18 and ive been on the Depo shot for 4 or 5 yrs now ,i hate being on it ive gained so much weight. When i started it i was about 90lbs im like 170lbs now. And im scared that being on it this long would make me infertile. I don't have periods either which isn't normal to me, being injected wit chemicals it just seems dangerous to my body even tho i haven't had any bad side effects. i just graduated HS i live with my mom she's one of thoes parents that dosent want to be a mom this early which is understandable i have college and other things in my way first. My 2 brothers have kids but im her babygirl im her ONLY daughter i understand her reasoning she dint want me to be a teen mom because she was a teen mom herself and she always tells me how hard it is to be a teen/single mom. Ive convince her to put me on something thats just as affective to prevent pregnancy but more safer than depo but which method should i use? the pill is outta the question because i would to take them on time (thats how my mom ended up prego). Please Leave your suggestions :)