I don't think it's a sign that you're going bonkers, that you're feeling bad.
I had a miscarriage, DS1, miscarriage, DS2. Even though I knew I could carry to term, and had a lovely son, the second miscarriage was really hard. My GP said I could have some investigations into it (as I was 34 at the time), but I ended up just booking myself a special private scan, to check for uterine abnormalities. They didn't find anything, but I felt reassured that I'd done something.
I remember when I was investigating this for myself, there were a few possible types of causes: immune system, hormones, genetic issues, and uterine abnormalities. From what I can remember, hormonal causes generally also cause fertility problems, which you obviously don't have, as you've had three pregnancies in a year. So you have three other possibilities. How late were your miscarriages? Did you have any early scans to check viability?
If you can eliminate some causes, and look into what diagnostic tools there are (and what treatment tools, too) then you can narrow down your choices for treatment, and maybe skip a step, if you want to go private. I just straight to booking a scan for uterine abnormalities, as it was the only obvious cause (and would have explained DS1's persistent breech-ness).
(I am totally not a medical professional. I also haven't researched this stuff for over a year.)