M.B.
I would try exposing her strangers with you for now. Let her get used to other people while safely with you. Invite friends over, take her to play groups, take her out to the store as much as you can. Let her interact with strangers first while you're holding her, then try letting them hold her for a minute or two, increasing it a little at a time. Explain to people that she is wary of strangers and that you'retrying to help her overcome that fear, so the expect crying and also understand what you're doing. In the end though, I wouldn't push it for now. She does seem young to have separation anxiety, but from you described that sounds like it, although most kids stop crying a few minutes after Mom leaves. Maybe this means it will be short lived. You know, intense but short rather than somewhat mild but drawn out. Hang in there!
M.