Postpartum and lithium?

I have a history of bipolar, anxiety, depression and PTSD. I had it all under control on my own with no medications, until my last daughter (who’s almost a month old) was born and everything came back for force. She was born with some health issues, nothing crazy, cleft palate and some other things, and it makes it hard for her to breath and eat without choking. So that fear i believe has triggered this. I did the responsible thing today and went to see my regular doctor, and he prescribed me lithium, and if it sits well with me(I don’t have issues or anything) then he’s going to prescribe another medication next week to go along with it.

Ill be 26 this October and Iv had issues since I was 12. Iv never taken this medication before, so I’m really nervous to start it. Has anyone taken this before?

Edit: I’m not nursing her anymore now and I wasn’t when I started the medication.