What do I do?

To give some context, I’m 5 months pp with my beautiful rainbow baby.

A few years ago I had a bad ectopic pregnancy that damaged my uterus and took out a fallopian tube.

When I had my baby I had a rough delivery, the bleeding couldn’t get under control and my baby was “sunny side up”

Once I hit 2 months pp I got my period again and have had it regularly and on time

Now my period was set for June 18th, it is not June 22nd and my period still has not shown up. I’ve taken multiple pregnancy tests and they all start negative but then they start to have a thin line show up. Everything I’ve looked up says the ink leaks. But this is with multiple tests. They always start negative then end up like this. I’ve NEVER had this happen before until now. What does this mean?