I would suggest you solicit the help of neighbors and friends by taking her out on walks and have the "strangers" casually toss a treat in her direction while they continue to walk by. They should not pause, talk to her, or make eye contact but rather just toss the treat as they walk by. Once dogs start associating good things with new people, you can then build up to stopping for a short greeting and slowly build up. Also, put a can of treats outside of your door with a note for visitors to take one and when they enter the house they should toss it towards her and keep walking away from her. There shouldn't be any pressure put on her but something great happens when unfamilar people pass by. You can then build up to her meeting them by allowing her to approach while the visitor is seated and the visitor does not make eye contact or acknowledge the dog, while allowing the dog to sniff and explore. Because it is almost always fear based, keeping the pressure off of them is most important. Slowly the person can start making physical contact with the dog but initially the visitor just tosses the treat and the dog then goes into a kennel or some place they feel safe away from the visitor. That is it for the first visit. Then you build up to the dog approaching and sniffing and then the dog goes away. Then a bit of petting and the dog goes away. You want the dog to want to be around the visitor more and for the contact to end before the dog starts feeling pressure or anxiety. Also, having people walk in front of your dog while on the leash with you and you casually strolling behind the strangers for a few minutes and then turning around away from the new people and ending the contact. Too often people go past the point where the dog starts feeling anxiety and the progress is lost. It's easy to do though because when you see your dog doing well with a stranger you want to prolong the experience. In actuality, short and sweet always wins out and you have plenty of time to build upon the sucess.
Also, take your dog to training and learn basic commands together. A dog that listens to you and can follow your commands is a much more confident dog that will form a closer bond with you. When you then pass people you don't know that don't have treats you can ask your dog to sit and keep making noises or gestures towards your face so the dog places their attention on you. If they are able to keep their attention on you and not growl or bark then they are heavily praised and given a treat by you. If the dog starts to growl, bark, or posture, abruptly turn them in a 180 and proceed at a brisk, commanding pace until his/her attention is back on you and he/she is behaving.