Hey Mel
I'm so sorry you're going through this, I just had a chemical last month as well and any loss is devastating. I got my period like normal when it was due. With my chemical I felt pregnant until the day I started getting bfns which was the reason I decided to test again so I felt my heart getting tugged quite a bit. And just so you know, most chemicals happen because of a defect in the dna, I got this from the what to expect website which I will link after
"WHAT CAUSES A CHEMICAL PREGNANCY
At the time of conception, an egg and a sperm combine chromosomes (23 from each partner) to form a zygote, which begins to grow through rapid cell division. During that process, occasionally a mistake happens, producing too many chromosomes or not enough. These chromosomal abnormalities which occur randomly and can happen to anyone are believed to be behind most early pregnancy losses, and they definitely dont mean you wont be able to get pregnant and stay pregnant in the future. However several risk factors (including advanced maternal age i.e., you're 35 or older and undiagnosed medical problems, like a clotting disorder or a thyroid condition) can put you at a higher risk of chemical pregnancies.
sadly chemicals are more common than we think and there is nothing that can prevent them
just know that it was out of your hands and please don't ever blame yourself
I hope I helped a little