How long?

How long does it take to make your cycle regular again after being on birth control for a long time (15 yrs). We are ttc and I have been off birth control since October 14. But we have had no luck and my cycle is crazy. I'll get my period 2x in one month then it will seem to be on track now this month I'm on the 45 day without my period (negative test yesterday). I am getting frustrated. But I have not been doing bbt or ovulation testing.  I just want to know how much longer before my period is at least normal again.