Definately go to the Dr regarding that past incident.

A 'healthy' couple can take 6-12 mths to conceive. There was no issue on my side of the family but it took us 13 months to conceive our DD and this baby is an IVF baby after 3.5 years of trying. My sister is older than me by 18 mths and is pg with her first, it took 8 mths and she is 37 yo. Everybody is different. Have you thought about charting your cycles to pinpoint ovulation so you know when to DTD? This was what made the difference for my sister. GL