If you were my patient, I would advise you that you are your dentist are probably correct that the pregnancy is making you more sensitive and is causing you to metabolize medications differently. Unless you will risk losing your
teeth, or infection (which would be worse than fillings) there is probably not a rush to finish your dental work.
That might give your pocket book a chance to catch up too!
In the meantime, take good care of those teeth and gums.