Cycle...

My cycles have always been regular, Now they are super hard to keep track, my last one started on the 30th of March and now it started on the 24th of April... I'm so confused. My fiancée is getting discouraged because we can't conceive. I haven't had any trouble getting pregnant before, I have 3 kids from a previous marriage. Any tips or thoughts I'm losing my mind from trying to stay positive all the time