Very very very unlikely that the abortion cause anything.
The biggest reason for taking longer is age. And I am not talking about 40 or 50. Your fertiolity begins to reduce from your mid 20s, and it will take a couple longer and longer to conceive as the years go by.
On average it takes at least 3 months for a couple to get pregnant. After a year of trying, you should see your doctor.
Remember to relax and keep it fun. Sex is not a job.