Short Lutheal Phase?

Me and my fiance have been TTC for 1.5 years with no success. (At least thats what I think due to my lutheal phase time period). I am currently on my second round of clomid and have confirmed ovuation on day 18 (like clockwork) for the last 3 months. My cycle is 28 days long leaving a 10 day lutheal phase. Should I be concerned although SOME doctors consider this normal and has anyone conceived with a 10 day lutheal phase?