Brown spotting

So I’ve posted on here a few times about my situation. But now something else has evolved. I started spotting brown a week ago. Went to the ER and everything looked good. I went to have a follow up ultrasound 3 days later and everything STILL looked good. I’m even measuring 2 days ahead. Now my issue is that they couldn’t take out blood because they couldn’t find a good vein. So they gave me lab paperwork to do blood work at a later date. Today I get the blood work done. But every where I’ve looked, they say brown blood is due to low progesterone. Has this happened to anyone gotten on progesterone medication or suppository and still had a healthy pregnancy?