Hellobee Boards

A couple of thoughts--
I agree with your therapist; it will be impossible not to worry about anything. Hell, I spent the first 12 weeks of both pregnancies worrying without any real cause as well. Finding ways to acknowledge and survive your anxiety about the pregnancy is the key thing. Do you think that your anxiety will lessen considerably when you hit 12 weeks? Even though some of these fears may be irrational, you are fundamentally a rational person and most of the causes for your concern would result in a miscarriage in the early weeks. If you think that you'll feel more in control come 12 weeks or so, I think you need some short term coping mechanisms rather than anything long term like meds. If avoiding yoga and swimming, and minimizing your time in the classroom is making you feel better and you truly think that in a few weeks you'll be able to let go of some of this anxiety then so be it. Let yourself do what you need to do to make yourself feel better. If you think that even after a healthy NIPT test at 11 weeks and good ultrasounds you'll still be stuck in this mire of anxiety then I think you need more of a plan for managing through the pregnancy.

Second, just some cold comfort on the smells issue: schools (and public schools in particular) are probably the most lawsuit averse institutions in the country. If there were any chance that the materials or products they were exposing students to could cause any degree of harm (including on a fetus), they would avoid it like the plague for fear of having a class action liability suit on their hands.
Also, at 5 weeks, I believe you don't yet share a blood supply with the fetus. It is more protected from environmental harms at this point than it is later on when the placenta has developed. At 7 weeks, when the placenta is developed and you are supplying the fetus with blood, then the baby's exposure to toxins (i think--anyone on here with better knowledge please feel free to correct me) would be dependent on the same mechanism as exposure to alcohol: the amounts that you are exposed to are first filtered through your liver before that blood is cycled to the baby. It is only in the event that your liver is unable to process and neutralize the amount of toxin that it is presented with that the toxin then makes its way into the blood that goes to the fetus.