Chemical pregnancy...3rd consecutive loss

Well I believe I had a chemical pregnancy. Earlier this week I had a positive test, and it had been getting darker until this morning. I took multiple tests including one tonight, and they're all lighter. I just missed my period yesterday, so this would only make me 4 weeks exactly. Back in April I lost a baby girl at 21 weeks, got pregnant in August and lost that one at 6 weeks, and now this. I also had a chemical in July that only lasted about a day, so I don't even count it. It makes no sense, I have a healthy 2 year old who I got pregnant with right away. With the baby girl, I conceived on the first try and there were no issues found. Her loss was unexplained. Now I can't seem to stay pregnant.

I've been seeing a fertility doctor and I've done all the tests and everything has come back normal. Same with my husband. Our next step is IVF, which we already started planning before this pregnancy. Could there still be something wrong with me or am I just having really bad luck?

Here are pics of my tests over the last 2-3 days with 2 different brands. The top tests are today's.