Rehabilitation for Margo

We got Margo from an elder that wanted a calm bulldog but got an aggressive one instead.Since Margo was little she used to bark and try to bite other dogs but the lady thought It was just puppy play and she didn't correct her in any way. Months later,she wanted to let Margo free on the streets(in winter time)because no one else wanted her due to her aggression and she couldn't handle her reactions but we decided to take her in. She has a good home now,love,food but that isn't enough. We thought we can handle her too but she's too much. We don't and won't give her up!!! But we need our help. I'm a college student with expenses and I'm a volunteer at dog shelters in my free time.I'm living a single mom who gets paid 350€ a month. Everytime Margo sees a dog I have to pick her up and carry her in my arms until the dog is gone because if I don't she will break the leash and go for the bite. If a child wants to pet her I have to be very quick in saying to not touch her and create distance becayse she will bite.On walks,she barks and pulls. At home,sometimes she even tries to bite us and she doesn't like strangers at all. I don't want our walks and our home to be this stressful anymore but we just can't afford to pay dog rehab too. So please,if you want to help,anything is greatly appreciated and brings us closer to our goal. Thank you so much.