How well is your thyroid regulated? Do you feel well and have good levels or did the doc tell you it is fine but you are still symptomatic? I ask bc a lot of docs are not good with thyroid. I got pregnant after 3 years of trying once my thyroid was finally properly treated (docs were over and under-treating it). I even had one totally useless endocrinologist so even that is no guarantee of proper treatment. I also did other stuff for fertility (diet, exercise, acupuncture and herbs) and I was in my mid to late 30's while trying so age was there but I was seeing an infertility doc and everything else checked out fine. I got pregnant very quickly once I got on the right dose, I definitely think it contributed for me.
One thing you could do to give you a clue is track your basal body temps in the am (google it if you need info). If you chart your temps you can see if you are ovulating, low thyroid can mess with that and the temp chart can make it very clear. Also if your temps are particularly low, though your doc may think you levels are normal, they may not be optimal.
Have you talked with your OB about it? If it's been a year you may want to investigate further if everything does seem well about your thyroid.
Another word about thyroid, my levels are currently "normal" but I have been so symptomatic and though normal, my T4 is in the high end of the range and T3 mid to low, so my doc adjusted my meds to get the T3 more in line with T4 and I feel so much better! My old doc just kept looking for other explanations for my symptoms bc my levels are "normal" but within the normal range doesn't necessarily mean optimal. So look at your symptoms as well as levels for the whole picture.