Marital relations are forbidden on Yom Kippur. In fact, no physical contact is allowed, just as if the wife were niddah. All harchakot as regards touching should be kept.
Since sperm live for at least three days (up to five days in fertile cervical fluid), relations the day before Yom Kippur could allow the possibility of conception this month. If the timing does not work for you to conceive (remember that there is a small margin of error in charting), do not get too discouraged. Hopefully, you will have more success in the coming months.
We wish you much hatzlacha and hope you find yourself in a healthy pregnancy soon.