Miscarriage & sonohysterography

I had a missed miscarriage on 6/12/22. First round of cytotec did not clear everything out so I had to take another round on 6/21. The ultrasound tech told me my uterus may be misshaped when we found out baby was not growing. Ever since then I have had anxiety about it and Dr is doing sonohysterography to make sure everything is okay. She thinks everything is but wants to ease my worries. Took a pregnancy test last night and there was still a faint faint line- how long until that goes negative? Also, how fast did everyone get pregnant after this procedure?