Pregnant on nexplanon????

How likely is it to get false positive pregnancy tests on the nexplanon?? I was cramping and feeling bloated so I literally just took one just to rule that out because I figured there was no way.. I've taken 7 test strips now and they're all positive. So a little back story. We wanted to have a 4th baby earlier this year. I got pregnant in June and lost the baby July 5th. We were going to try again immediately, like the Dr told us we could. But then about a week later I applied to college, my husband and I sat down to talk, and I started freaking out about getting pregnant again so soon this time after a miscarriage because I was terrified I'd lose another and I just wasn't ready for that. So I got ahold of my Dr and I got on birth control pills until we decided for sure what we wanted to do. Then my husband and I decided that I would go ahead and get the nexplanon because I decided to go to college instead of have another baby right now. We decided to wait until after I'm done with college to have one and since the nexplanon was 3 years, it was perfect. The pregnancy test at the Drs office was negative before they inserted it. That was Friday the 14th. I'm sorry this is so long but I'm freaking out and desperately need help.