3rd miscarriage

In the last two years I've had 3 miscarriages. The first two were to my ex and my third was to my partner now. I had multiple blood tests done and all came back clear. But does anyone else think that the reason "your body just wasn't ready" isn't really a reason? Like I don't understand how?😭 first pregnancy I was 4 weeks, second was 6 and then the third I thought I was almost 9 weeks but the baby stopped growing at 7w3d.😪 so if my body isn't ready why does it allow the next pregnancy to go further then the last 💔

Sorry if it's too long.