Vaginal Discharge, for 14 yr old?

HI, im a 14 yr old girl, since november i have had a clear mucasy nasty discharge coming out of my vagina, it comes out a lot (at least 1/2 cup a day) and it smells way bad, i have it about 3 weeks every month. Sometimes i have my period and sometimes i dont. I dont know if i have some really weird prob. but if u can help me that would be awsome, i dont have any pain, just this smelly clear liqued UGH! Do i have diabetes, or some other health problem? MY mom has multiple sclerosis so she is kinda worried, if u can help me that would be great!!! Thanks!