Just to reassure you, our youngest dog (now almost a year old) was like this when she was younger, and is still not a big fan of crowds, but we had visitors yesterday and she was very interested in saying hello. She is also increasingly enthusiastic about greeting strangers when out on walks. It helps that we have other dogs who are very sociable with people, but don't panic, just keep introducing her to situations that don't scare her, but push her to the edge of her comfort zone. Get her happy with that, and then move on to the next phase.
Also, when she's a bit worried, don't croon at her with the whole, 'Oh, sweetie, it's alright, don't be scared' because you are effectively rewarding her anxieties. Be very alert to her frame of mind, but aim more for a bit of jolly hockey sticks: 'Oooh, look, that's new, want to take a closer look? No? Well, never mind, how about we look from here, that's all fine, isn't it?' Of course she won't understand the words, but the tone will convey that you are unafraid and can't imagine why she should need reassurance.