Need Help!

I had my mirena taken out April 22, had my first period the following Friday I think it was 25th or 26th, by June it was going back to normal the 28 day cycle but I had no period in July, I am now 20 days late and I've taken about 6 hpts and all have been negative I spotted a little light brown on the 17-18 in July and spotted just a little today could barely notice it, I am a little over weight maybe my body doesn't have enough of the hormone yet BC of that idk, I need some advice I'm very nervous but I really do want another baby I think I'm losing my mind! Sorry this is so long.