That depends on . Which tea you are talking about. T is recommended that you not drink nettle leaf, fennel, sassafras, rosemary, hibiscus, ephedra, licorice root, raspberry leaf, anise or sage tea. Encourage you to limit caffeine intake -so if you drink white, red, yellow or green tea- try to make it decaffeinated.
Yes. Nobody that you will meet in the course of your day (or lifetime) was incubated under pristine laboratory conditions. Most everyone's mother did a little bit of this and that, smoking, alcohol, caffeine, dietary indiscretions etc. The same holds true worldwide and over the course of human history. Most of us turn out okay. Just keep in mind "everything in moderation", and avoid known problems.
Yes. Caffeine during pregnancy is a debatable topic. I usually suggest that one caffeinated drink a day while pregnant is thought to be safe. You want to avoid triple lattes, especially if you drink them more than once a day. Herbal teas can have compounds in them that are portentially dangerous to a growing fetus. Stick with the mainstream teas if you must and limit intake to once daily.