Fired for being pregnant???

My work has been so unbelievably horrible to me. I ended up turning in my two weeks notice, making my last day September 25th. However, on September 24th I called work to let them know I would be late because I was throwing up the night before very badly. My boss told me I would have to work later hours to make up for lost time and when I told her I couldn't because I had a doctors appointment that evening she made the decision to let me go that day. I didn't know that so I went to work that Thursday and when I arrived I coworker, another member of my management team, told our mutual coworker that I was not allowed on the premises. What does that sound like to you?  To me it sounds like I was terminated. I i'm so blown away by the atrocities I face on a daily basis for almost a month and a half and then they have the nerve to fire me. I have already composed a letter to corporate and will be sending it to the head of HR, as well as the president, and founder of the company. I have spoken to a lawyer but I can't afford it. Any suggestions as to how to help my case?