A.F.
I work with children birth to 5 years old, focusing on social and emotional development. What you are already thinking of doing is good. Your daughter's reactions to others and possibly the new baby may be because she feels her relationship with you threatened in some way. She wants mommy all to herself, which is actually appropriate for her age. She is supposed to be more possessive of you and needier during this time than any other. Another thing you can do, if you haven't already, is begin to talk to her about the changes that will happen and begin to help her understand how to cope with those changes. For example, "you will have a new brother/sister soon and sometimes mommy will need to take special care of the the baby because he/she is so little and needs extra help. That means that sometimes mommy won't be able to play, but mommy will always make time for her special girl and I love you very much." Or something similar that fits your relationship with your daughter. All she really needs to know is that your divided attention doesn't mean abandonment of her, which is likely her fear given her age and developmental needs. She will likely benefit from lots of preparation through conversation and books about becoming a big sister and lots of reassurance once the baby arrives. Good luck.