Really sorry to hear, OP. Those are very sad, dark days and I hope you're looking after yourself. 
Last year, I had a missed miscarriage, then a miscarriage 2 months later, then an ectopic another 2 months later. No investigations offered, because 'bad luck' and 'not identical events'. It was a very awful and lonely time. Having given up on TTC a bit, 4 months after that I fell pregnant again with what is currently a very active bean, 21 weeks and kicking away. All looks well (fingers crossed!).
The only thing I did differently, like PP, was to start taking low dose aspirin as soon as I got my BFP, alongside the usual prenatal vitamins. My GP wasn't keen on the idea because of possible complications like stomach ulcers but, frankly, by that point, that seemed a small price to pay. So we agreed that I'd note the medical advice/concern but carry on anyway since it is largely safe to do this and many pregnant women do get prescribed low dose aspirin as treatment (albeit for an identified condition). At 14 weeks the obsthetric consultant said it was the right call and that sometimes this works, excactly how or why isn't yet fully established and studies are mixed. So he said carry on but get the gastro-coated one and see GP if I get (tmi!) blood in stools or excessive bruising. So far, so good. Obviously I freak out every time I've eaten beetroot and forgotten that I had!
Will never know whether this made any difference, but even if it was a placebo it seems worth it in my situation.
All the very best to you, hang in there!