Hello, I Am Wondering What My Chances Of Being Pregnant

Hello, I am wondering what my chances of being pregnant are. I mac currently on the nexplanon birth control implant and have had sex about once a week for the past three weeks. I am not trying to conceive at this point in time and I am a little on the edge about it. Since I am on nexplanon, I don't get my periods anymore and haven't since it was placed in June 2015. I spot all the time, there's no schedule for that for me. I am also feeling full all the time and when I eat I feel sick. Those are the only two symptoms but they are also likely to be something else as well. I just want to know, what are my possible chances of being pregnant right now if I only display those two and I a man on nexplanon?