Difficulty getting pregnant....my age???

I'm 33 and my SO is 37. We have 2 kids and have been semi trying to have a third. I had my son when I was young, at 18 and my daughter almost 11 years later, she's 4 now. My period when I got pregnant was very regular and with my daughter it wasn't but I estimated my ovulation day by counting the days. I got pregnant quite easily with both of them. My period is still very irregular, which is how I came upon Glow to begin with, so I could track my cycles and plan conception easier.  We've been trying for about 4 or 5 months now, and I say 'semi' because we're not very good at making sure we have sex every day during my fertile window, but I still feel like I should have gotten pregnant by now!!! I thought maybe because of our ages perhaps his sperm count was low or my egg quantity/quality weren't optimal any longer. I bought a test that checked both his sperm count and my eggs and both came back with normal results. I'm getting a little discouraged. I feel like I'm being slightly insensitive for losing faith this soon since some couples try for years with no success. My question is, are there any other women I'm my similar situation/age range that are experiencing the same difficulties???