why does this keep happening?

I am so confused/aggravated! I get pregnant easily, but I miscarry around the 5/6 week mark! Even have blood tests that show my levels increasing and my progesterone was normal! I have hypothyroidism that is controlled with Synthroid. I got pregnant with my other 2 children on the first cycle off of BC and never had this issue! This will be the third time I've miscarried early like this! It's so discouraging! I see all the posts on here about people just hoping for a positive hpt, but I can't even get excited about it! These are pictures from around the 11 DPO- 16 DPO and I was feeling hopeful because the line was getting progressively darker 😔 Anyone been through this that can give me some insight to what I need to ask the Dr to check for?