Possible Infertility?

I have been pregnant once before, but it was years ago. I lost the child as well. My fiancé and I have been trying for a while now with no luck. Is there a possibility that I am infertile? Even though I’ve been pregnant before?

I’ve recently started tracked my ovulation with a kit but it isn’t correlating at all with the apps that have given suggestive ovulation days. I’m not sure what to do