Am I crazy?

I should disclose that i have 2 children, age 5 and 2, and on April 3rd I will have had the Nexplanon implant for 2 years. At first my periods were wonky but then they basically became regular. I might skip a month every 6 or so, and sometimes the next two cycles would be a little heavier and maybe a few days closer. However, this has me worried. My OBGYN is of the mind that I absolutely can't get pregnant on this thing. Yet I have seen women on here saying they did. I redownloaded this app in January, which is when things got stranger than ever before. The last period I missed was October. Since then, November and December were normal. The first one in January was on time and HEAVY. I bled through supers in 20 minutes, and ultras in 3 hours, if not 2. I figured, okay whatever, because

while I havent had a heavy one like that in a while, maybe I was overdue. Then it stopped. And they have stopped and started as shown. the rest of them were regular flow. The one that started recently is weird. Its old blood (brown) and only very little. If I wipe its there mixed in with my normal woman fluids. The other day I didn't get a chance to pee until I got home and there was a little on my underware. I have never experianced this. And if it was a period starting like this, by now my body always started fully bleeding. I have never has so many periods, so close, or this "spotting". My OB refuses to even run tests, but I need to know if anyone has experianced this, and what it was. 2 years guys. I have had this thing for 2 years and not gone through this.

Note: I am taking a pregnancy test tonight, but I may not be very far if I am pregnant.