I went on 40mg of Celexa when I was breastfeeding my son. I only made it 4wks of BFing with my daughter and she ended up going on Soy formula because of sensitivities. I was determined to BF my son as long as I could and we made it 9mos. I struggled with a low supply so he did have to get formula to gain weight, but that's a whole different issue.
Anyway, I was prescribed 20mg of Celexa at my 6wk appt and didn't take it because I was scared of what it could do to my son. I then talked to the pharmacist and a lactation consultant and did my own research. I started back on it when he was 8wks old and just kept a close eye on him. He didn't have any side effects that I know of.
I guess my suggestion is to maybe find a different Dr. Someone who is willing to work with you. For me, the depression was so bad I didn't want to be near either of my kids. Getting stabilized again helped me to finally bond with my son and interact more with my daughter. You can PM me anytime if you'd like to talk. Hang in there!