i would def speak to your psychiatrist...maybe you could gradually reduce your dose over a couple of months and see how you go. or you could look at changing your meds to something which is safe to take during pregnancy.
i wasnt taking any medication when i fell pregnant, but i found that my depression did return during the pregnancy. it was just a hard time for me, but i am convinced that that was due to the stress my job was putting me under. once i was signed off work i felt a lot of relief.
having a baby is really stressful and tiring so there will be times when you arent sure if you can cope but i think thats true to most mothers, especially first time ones. pregnancy can also be a strain on the body, it isnt always plain sailing and some women will suffer throughout be it with morning sickness or something else like SPD or iron deficiency. so i would suggest that you go into it with an open mind...its not to say things will be like that, you may have a wonderful pregnancy! i really enjoyed mine, except for the terrible acne i suffered i loved it and miss my bump every day!
whatever happens, good luck

if its the right time for you as a couple, then it will happen one way or another! but i do think you should work closely with your doctor or psychiatrist to make sure that you go about it the right way
