Clomid - Works Sometimes?

Alyssa
Hello ladies! Desperate over here. 
I started my first two cycles on Clomid 100mg Day 3-7. Ovulated Day 17 both times. 
3rd cycle I took a break since my husband was traveling during anticipated ovulation. 
4th and current cycle I haven't ovulated and I'm on day 25. 
Anyone else have successful clomid treatment and then it stopped helping them ovulate? Any feedback would help!