I was intimate with my partner on march 18. when he was removing himself the condom came off. it was not stuck and he was able to take it out. ovulation was predicted march 9-17. my next cycle is predicted mar 29. is there a chance of pregnancy?

Protection usually is complete in this situation. However, it isn't possible to be certain. This sort of thing is one of the things that makes reliance solely on condoms a poor contraceptive choice. Couples who use only condoms, and use them properly and consistently, have a 90% reduction in conception rate (i.e. 10% failure rate), compared with 100% protection by hormonal contraception, IUD, etc