Do you have this issue too??

Question. I have a normal 27 day cycle each month. 5 day period and almost always ovulate on day 11-12. We have two girls (6 & 12) and we’ve decided to try for a third. We’ve been TTC since June had 1 miscarriage. Just confused as to how my cycle is so normal, but having such a hard time conceiving again. Im 30 years old and my husband is 37. Any ideas?!