Well, not a great sign- this is why three high temps are necessary to confirm O. But always keep in mind that one temp does not make a pattern. And really, don't bother with taking your temp over and over again b/c often it will just mess with your head. The first temp is the right one for that day (unless your thermometer is broken or something).  If you get several temps that dip like that, then no O and expect another patch of EW and another spike OR breakthrough bleeding. But if it goes back up and stays up then there is a good chance that you did O on CD 23.  Ovulation was dubious last cycle as well and there is a possibility that you're not regularly ovulating, which would explain your difficulty TTC. If you are in fact ovulating, then you have obvious dips in progesterone/surges in estrogen during your LP, which could make sustaining a pregnancy difficult. This is where charting is simply invaluable. If you have several cycles where it appears that you may not be ovulating or have an infertile LP, then you can take that information to a reproductive expert and decide what steps make sense to take next.