I think it has to do with the hormones from pregnancy and how our bodies have changed. You may find it goes back eventually, but it could stay as it is. I'm my case, I'm happy if mine stays like it is, I've always had trouble with my cycles. Turns out I have PCOS, so I used to have excruciatingly painful cycles every 2-4 months until I went on birth control. Then, when my birth control changed (migraines, can't have estrogen), I was having 12 day cycles 😢. Got checked, and it was "normal" just my bodys reaction to the new meds. Now on my birth control, so far, my cycles are within normal range, so I'm happy and hope it stays.
yeah mine is much longer now even after 2 years. it was so inconsistent for a long time i thought i was pregnant every month lol