Could this be ectopic?

I am currently 3 weeks late. I've taken a pregnancy test at 2 days late, 2 tests that next week and last week I took 2 more. All negative.

I started having tender back pain (mid to low) a few days ago. I've also had on and off again cramping to where it felt like I was starting but no bleeding. I've had nausea here and there like my previous pregnancies but I also get that before I start also. I'm super scared I've waited too long and it could be ectopic. I've read some women get negative and positive PT? Just trying to get some insight! I plan to make an appt with my GYN on Monday but until then, help!!