ttc but iiregular periods and i dont no when i ovulate

so basically the subject says it all, me and my husband have been ttc for over a year with no success as my periods are so iiregular i dont no whem im coming on or when i ovulate so its really depressing me, all we want is to have baby #3 but its been so hard. i really thought i was pregnant this month as ive been getting cramps for over 3 weeks and no period so from cycle day 28 i have been testing and i started af on cycle day 37 with disapointment but i dont no if it was a proper period as it wasnt heavy like when u first start it started for 1 day then stopped then started the next day so i dont no whats going on, i have taken tests but all negative so im really depressed about it, with our 2nd it was litrally months before i found out i was pregnant and now this time its taken a year, im off to see my doctor about it as im really annoyed about my periods being iiregular and see what he says, sorry for the long story lol, just wondered has anyone been in the same boat tried for ages and feel disappointed when af comes.