I am 40. ttc for 6 mos. cycle ranges from 23 to 26 days. lmp dec 8 and before that nov 12. i have taken 4 different kinds of epts. all neg. ?

Trying to conceive: It is not unusual for at women in the 4th decade to have difficulty in conceiving. Since your cycle is short I recommend that you consider LPD (luteal phase defect), check your progesterone level and have an EB (endometrial bx) performed a week after ovulation. I suspect that your progesterone level is low even if you're ovulatory, and this is easy to remedy with natural vaginal progesterone.