Early period during break from ttc?

Is it normal to have a weird cycle the month after doing medicated cycles? For feb, march, and april i did iui with clomid the first 2 months and femara the 3rd. All were bfn...so we took a break for may cycle. I had my period may 3rd...and was on cd 20 yesterday when i started my period again after dtd with my dh. I normally have 33 or 34 day cycles...so im very early...i should have been ovulating.