I think you are doing fine! If you feel uncomfortable with the extensive testing, than don't do it. If they make you feel guilty, bluntly tell them it is your body and your baby and you will do what you feel is best.
Take "emergen c" a buffered vitamin C supplement and also take your prenatal vitamins including an extra B vitamin complex with folic acid.
In the middle of your 2nd trimester start drinking red raspberry leaf tea. If I were you I would drink 3 cups a day (or more if you can) It works as an awesome tonic for the uterus and prepares that part of your body for birth. You can even make into an iced tea, just don't use sweetner.