I'm going to be completely honest with you here - there are no studies into the effect of aripiprazole on the developing embryo, and therefore the manufacturers only recommend its use in pregnancy if the risk of you being off the medication would be a bigger risk to the baby - eg, if you would become extremely depressed or manic. With sertraline there are very limited studies, and with some SSRIs there is evidence of withdrawal in the baby when it is born - again it is recommended that it is used in pregnancy only if the risk of you coming off it is greater.
Obviously, your psychiatrist knows more about your present state of mind at the minute than I do, and I would urge you NOT to stop taking your medications without discussing it with him first, because stopping them cold turkey can have horrible side effects for you. The most important thing to do right now is find out whether you are pregnant or not, because you might be getting worked up about nothing. Good luck.
Thank you so much for your valuable advice.