I don't understand

You are over 40. The possibility of having trouble conceiving is there and is very real, regardless of your FSH number and how fertile you've been in the past. I don't understand how your nurse could tell you that everything looks good. Fertility cannot be taken for granted over 40, even if your FSH is low. Sorry if this is obvious and I'm being obnoxiously paternalistic, but there's plenty of women on these boards lamenting that they weren't aware that fertility declines during a woman's early 40s.