Cycles after open myomectomy

Hi all.

I had open myomectomy 3 months ago to remove 18 cm transmural fibroid.

I had my first period 24 days after the surgery. My second and Thies cycle were also 24 days each. Now, all of sudden I got my period on day 18 of my 4th cycle. Im feeling so defeated. Is anyone had similar experience. Thank you.