Hi Upsy
I took some zopiclone while pregnant (approx 30 3.75mg tablets during the whole pregnancy) and was on haloperidol at night as was diagnosed with bipolar while pregnant.
I was on roughly one 3.75 tablet per night before pregnancy but was able to reduce that by firstly cutting or snapping the tablets into two and then quarters, and by allowing myself to take zopiclone only every other night and then only when needed (rarely).
I was referred to a specialist perinatal team who were very knowledgeable about medications and risks for mental health drugs in pregnancy. I was really concerned about having medication in pregnancy but they were able to print off medical literature which gave the risks compared to the baseline for me to make up my mind.
There is a risk in taking anything while pregnant, (and this risk depends on the drugs and the quantity you are taking - and doctors would not prescribe you anything that absolutely is unsafe in pregnancy), but this also has to be weighed up against your wellbeing and the wellbeing of your baby as your stress hormones do also cross the placenta as well as any drugs.
I am currently on Seroquel and have asked my MHT about what would happen if I wanted to ttc and they said that i could either stay on it, come off all medications or choose an older type antipsychotic - not because seroquel is unsafe but there is more data available for older drugs. For ethical reasons no drugs company will trial drugs on pregnant women, obviously.
Your seroquel doesn't sound very high - but if you are worried you do need to speak to a mental health team - preferably one that has experience with perinatal health.
Fwiw just to put things into context, my psychiatrist told me that the risk of any defects in the fetus is naturally around 4.5%. The risks in women who have taken therapeutic drugs in pregnancy are just fractionally over this baseline.
Congratulations on your pregnancy and i hope you can speak to a specialist who can discuss your needs. Good luck!