Can BBT be off on clomid?!?

This is my first month of taking clomid. I had a positive opk on CD 12 which would have been 7/30. So I was thinking I actually ovulated on CD 15 but from my bbt it looks like it was on CD 17. I'm not sure what to think because last night I had a little bit of blood in my CM when I wiped. Sorry TMI!! Anyone experience this?! What day did I ovulate?! Glow doesn't mark my ovulation or fertile window correctly because my cycles have been all over the place