pregnant on nexplanon

i had sex the day before my ovulation week and he came in me. he told me he felt himself cum more than usual. i have only had nexplanon for a month now and i’ve been bleeding ever since i got it. i had sex with him after 2 weeks of having the implant. now i’m starting to stop bleeding and blood is looking more light/brown. could this be a sign of pregnancy or is it just the nexplanon?