Five losses in 18 months

I've just suffered my fifth miscarriage in 18 months. I've had tests done on the Nhs but everything has come back normal. I was told to try baby aspirin this time but it's made no difference. Can anyone offer any advice? Most of the miscarriages have been around 5/6 weeks, I did get to ten weeks on my second pregnancy but my symptoms vanished at 6 weeks. I have never had an ultrasound while I've been pregnant and feel like we have no more answers now than we did after the first miscarriage. Feeling deflated and helpless. The only advise we've been offered by medical professionals is to keep trying.