DONT PANIC!!! I was right where you are now after the birth of my #2 - my boy. I wont go into the detail of how I came to the point where I needed the drugs - its not relevant and wont help you, so let me tell you about from when I took them:
It will take about 8 weeks for them to fully start working for you, so dont be too disappointed if you are not noticing anything just yet. I would say within about 10 days I was feeling a little better but I dont know if that was because I was finally DOING something about it, or the drugs themselves. I was on Prozac 20mg a day (I think? That sounds about right!) If after a few weeks you are not noticing any change at all you may want to have a word with your doctor about upping your dose slightly, or changing to a different brand, but give it time. 8 weeks really isn`t as long as it seems and it is something to look forward to. By the beginning of April you will pretty much be there!
I was on them for a year and then weaned off. I havent needed them since, but I wouldnt hesitate to go back on them if I needed to and I am more aware now of the signs and symptoms that I need to. My only regret in the first place is that I waited so long suffering in silence (or not! I had terrible mood swings!) just because of some stupid outdated notion that these drugs were for "loopers" and I should resist resist resist. What a load of nonsense! You have a kidney disorder - you take medicine. You have a cold - you take medicine. Why the hell not for depression and anxiety? I now say "All the prettiest Mums are on Prozac!" and called them my "Vitamin P`s"!
I have moments where I go through anxiety and panic, BUT alongside the Prozac treatment I did a LOT of research on how to manage my anxiety, a bit of CBT, and now for the most part I am getting by fine. The hardest part of the whole process was finally relenting and getting myself on to the meds. You have done that, and not waited nearly as long as I did! Well done you! I couldn`t understand why I was so miserable after the birth of #2, when after #1 I was so happy and competent the whole time.
I have 3 kids now, and it has been about 3 years now since I came off the Prozac (I stopped when I decided to have #3. I often joke that had I not BEEN on Prozac I probably wouldn`t have ever even AGREED to try for #3 but there you go!) I have NOT had any recurrence of the PND with #3, and this despite a very traumatic birth (including my obstetrician eventually hitting on me would you believe!!!) and the utter utter chaos of 3 kids under 6 and a very hands off husband.
So in conclusion - in my humble experience and opinion you have done exactly the right thing, you will get better, just be patient and enjoy being Pretty on Prozac! xxx