Confused and concerned

Kailey • Anxious 21 year old who is looking for a home

So I have been somewhat getting my period. I got the Nexplanon insert on November second or 2018, and I now get light bleeding with dark brown discharge wvery 9 to 12 days, with cramping. Is this normal for Nexplanon? I also feel like I'm gaining weight, but I'm not sure if I actually am or if I'm just being too self concious.