Sorry for your losses.
If you change the language, what you are having is very early miscarriages (I hate the term chemical pregnancy, I feel it’s an attempt to minimise this sort of miscarriage).
Miscarriage always has a medical reason. We don’t necessarily know what the reason is, and you might never find a reason, but it’s important to get these investigated properly. There are treatable conditions that can cause this sort of early miscarriage - low progesterone, some clotting conditions (I’ve got APS which can cause very early miscarriage by interfering with implantation), thyroid, vitamin deficiency, and I’m sure many other things I wouldn’t have a clue about.
If I’d listened to my GP waffling about my age, egg quality, and chromosomes, then I’d probably still be childless as the only things that will get my body through a pregnancy are aspirin, heparin and progesterone. He was well meaning, but GPs aren’t fertility experts and I insisted the hospital referred me for further tests after my third miscarriage (although I’ll always be annoyed about that GP as it should have been done after my second and he cost me already limited time).
I’m glad your GP is supportive - it sounds like they plan to refer you for tests if it happens again. Check your local recurrent miscarriage clinic to see what their requirements are, for some it is 2 miscarriages. Waiting lists can be long so if you can get referred now it’s worth it.
I hope you don’t need it and everything is fine next time, chances are it will be but if you are already on their waiting list often they will bump you up to appointment if you get pregnant while waiting xx