Your worried about two months seriously? You only have a 25% chance of getting pregnant. Most couples takes 6 months and a doctor won't even look at you unless it's been 12 months of trying. Just keep practicing! :)
This same thing happened to both my sister and a good friend of mine. Bam, pregnant right away with first and then difficulty with second. With my sister, she south help with a fertility doctor. With my friend, she took clomid and had her second child 7 years after her first. There really could be nothing wrong. Remember the best way to get pregnant is to track your cycle and on day 10 of it, to begin having sex every other day for the next 10 days. But after 5 years, my suggestion really is to talk to your doctor about this. Come back and let us know how it is going!