I haven't had PND but have had post natal anxiety which I still take citalopram for. I found seeing a psychologist really helpful. I too was so ashamed and embarrassed, for some reason I thought I would cope really well with becoming a parent (who knows why I thought that!) but found it much harder than expected.
I did feel a bit 'off' and nauseous the first couple of days on medication but it settled down. Other things I found that have helped me are doing more things for myself as DD has gotten older, getting back into exercise, catching up with friends both with and without kids, and even just simple things like watching TV shows I enjoy and reading. I still have anxiety but it is nothing like before.
Wishing you all the best in your recovery and remember that 1 in 5 people will experience a mental illness in their lifetime, your certainly not alone.