So I have 3 girls a10,7 & 2 year old, which I’m truly blessed with. The hubby and I decided to try…

So I have 3 girls a10,7 & 2 year old, which I’m truly blessed with. The hubby and I decided to try to see if we could get prego 6 months ago and nothing has happened. We always got pregnant right away with all my 3. I turned 40 this September. Could it be because of my age it’s not happening? I’ve been using ovulation kits for a couple of months and saw a positive twice and had sex at and around the time of it. Just curious if anyone has gone through this. Thanks