help me out with the timeline

As much as i’ve rewatched this show, I still get confused about their ages.

In season 2, episode 10, Ilana is turning 23. Abbi is 26 or soon to be 26.

So they’re roughly three years apart. Well then season 5, episode 1, Abbi is turning 30. Have 4 years really passed in two full seasons? Or do I have something wrong here?