question about meds

I'm on 75mg of Zoloft and am taking it at night. I seem to get through the day, though the anxious thoughts still seem to come in and out. But around dinner time each night, a couple hours before I take my next dose, it seems like the uneasiness and anxious thoughts increase. Why do you think that is? Is the dose not high enough? Or am I metabolizing the current dose too quickly due to my pregnancy? Just wondering about others thoughts. Going to my psychiatrist tomorrow so I'll be running it by her also.