Hello
Supposing you had a dominant follicle on the 17th of this month, following the trigger short it takes 24-36 hours for the egg to be released from the follicle. That would be on the 19th/20th. However, following intercourse the sperms survive for 2-3 days. This is the reason why your doctor would have instructed you as you have mentioned.
So in conclusion, there is a fair chance that you may conceive if all other parameters are normal.
Health Tips
Do not worry or regret that you havent tried exactly as per your doctor. All being normal the chance of conceiving in one cycle is roughly around 15%. All the best!