You should definitely go see your doctor!
I breastfed for 15.5 months, my LO is almost 22 months now and my period is still irregular. Getting closer to being regular as of the last month or 2. Everyone is different. Be patient, it'll come back to being regular eventually
11m pp my periods still irregular around every 2m although last month it became shorter I also breastfeed aswell but if you are concerned or wanting to try for another baby go and talk to your doctor
12 months pp and my cycles are still like this but I do breastfeed and also have PCOS so it’s absolutely impossible to know what the hell is going on!