Only getting positives on frer for the past week

It’s been a weird week of pregnancy tests for me. It started with getting positive tests last Saturday on a couple of different hpts and now almost 5 days later I’m only getting positives on the frer and no other tests. However, the line on the frer is getting slightly darker. I also have taken a first response digital and first response rapid result and those have come back negative as well. It all just seems super weird to me at this point. These are the tests from this morning and last night. The top are from today showing my positive on the frer. The bottom first response is the rapid result from last night and then two generic target brand tests. I’d figure after 5 days my tests should be getting darker and I should be getting positives on more than just the early result tests. DPO is unknown since I have not had a period since having my baby 3 months ago