Is it considered breach of contract if I have been waiting for eight weeks to start working to no avail?

Employment firm (agency) called me and said they'd be interested in having me interview for one of three positions, all with the same company in the greater area. The first position was deemed not to be a great fit, and somewhat far from my home, and then a week later they called me for two more positions they had which were closer and I was qualified for. They set up an interview for the last week of September, which I went to and everything went well. The employer (client) is a large company and has a background check and other hoops to jump through which I am not privy to, as part of the hiring process. I was told this process normally takes 2-3 weeks. A few days later, first week of October, they sent me a written offer to start at $75,000 annually for the client plus benefits, considered at will employment. It was a very basic contract but said my expected start date would be around the middle of the month. At some point the paperwork was taking longer than expected and they decided to subcontract me out under another employment agency that often deals with this client. I drove 45 minutes and filled out a bunch more paperwork on a Friday, November 14 and was told my start date would be the following Wednesday in all likelihood, since Monday was coming up fast. The following Tuesday, I received a call from the first agency telling me this was plan was not going to happen and they were going to resume going to hire me on directly. They were willing to give me a bump in pay to $83,000 annually plus benefits because it was taking longer than expected. I then called them back on November 21 to see what was going on because I still hadn't heard anything about the starting date. They said the following week was Thanksgiving and only a 2-day week for the client so it was unlikely. And then said 12/1 or 12/8 seemed more possible. Even though it's "at will" and after almost 8 weeks of waiting, I've all but given up and today find myself in limbo.