I need some opinions!

I got my IUD out early Dec. had a faint positive pregnancy test January 12. On January 17 I started bleeding, I assume chemical pregnancy. My pregnancy test was basically negative the next day. I didn’t even go to the doctor because I had a pretty normal period that was only a day or two late. If I hadn’t tested early I would have never known. Well, we decided to wait a cycle to really start trying so my husband used the withdraw method around the time I was supposed to ovulate. Well its now Feb 17 and no period. I had some cramping Wed and Thursday (Feb 13 and 14). I swore I was about to start my period but never did and now cramping is gone. It felt like I was going to start any min. No positive pregnancy test either. Has anyone else ever experienced anything like this? I didn’t take an ovulation test so I’m not exactly sure when I ovulated. It’s just strange that I experienced this cramping and didn’t start my period. That’s never happened. Now no signs at all of my period coming. Any opinions on what could be happening in my body?