When will i ovulate?-help conceiving!?

my husband hd a vasectomy 10 years ago. he is 16 years my senior. we have been married almost 2 years and together almost 5. After doing the research im learning that the vasectomy he had long ago along with his age(38) chances are slim of conceiving that way with a reversal,not to mention cost! So we decided to get a sperm donor. We know the donor and he has offered to come over on the days needed. Only thing is im not QUITE sure when im ovulating. I usually start one day later on my period. EX: if i start on the 14th of february ill start on the 15th of march 16th of april etc. Does this mean i have a 30 day cycle? the first day of my last period was may 17th. So if i do the 14 days after the first day will i be ovulating around the 31st? what would be the best 3 or 4 days to concieve? Also, were not doing it the conventional way so any tips on at home artificial insemination would help to! Appriciated!!