Hope someone can help!!

I'm 38 and been TTC for the last 8 months now.... So far no success...

My concern is that my AF has become very short to just 2 days from 5 over the past 3 months and I'm worried. My cycle is regular at 31 days. I did have a bit of spotting 3 days before my last AF but it still came but was very light and only 2 days. Has anyone any suggestions? Blood tests have so far been OK. I'm just fed up of the constant string of negative tests....

Thanks ladies x