Birth control

So I'm on the birth control called depo and I've been on it for about 10 months, and ever since I got it my period is really messing up like one month it could all just be like a brown discharge then another month I miss it, or i have a heavy flow! The doctor said that I would regulate it, but it's just going crazy and I'm really hating how my body feels when I miss it or have that brown discharge, it's really weird.