How old was Liza when Caitlin was born?

In S1, Liza said she quit working at age 25 to raise her child, but is Caitlin a 15-year old living in India and going to Goa with a guy for the weekend? In S2, Caitlin drinks wine and gets a tattoo, so presumably she's 21 or at least 18.

So did Liza have Caitlin at age 19, but waited until she was 6 years old to quit work and raise her? Was she a mom all through college? The timeline doesn't make sense to me.