The short answer is that it 'should not' affect your transaction experience at all...if anything it may affect your agent's experience in the transaction. Most agents will affiliate with more than one company during their career - and most busier agents will almost always have listings and/or purchase transactions in contract at the time of the switch. Really there is almost no opportune time for an agent to make a switch. You should not experience any speed bumps as a result though - your agent will likely complete this transaction under the company where the transaction originated.
Your contract is with the broker, not the agent. The agent, as others have said, will most likely support you through this transaction and still be compensated from his original broker for the effort so that should not change anything on your purchase. However, if you feel more comfortable, you can contact the broker to have him assure you of this directly, and address any and all concerns that you're having The less stress for you the better, but this probably won't affect the level of service you receive from your buyer's agent.
I am sorry to hear that you have had a difficult time during your home purchasing experience. Since you have indicated the word "escrow," I am assuming that a Ttile Company and Escrow Officer has the file for the property that you are purchasing. If that is the case, then no, just because your realtor changed companies does not mean this will in any way affect you. I hope that your realtor will be at your closing just to make sure that everything does go smoothly. You may want to call your realtor and ask if she will be present during the signing. This is always a good idea and something that I strongly believe in and do for my clients which helps to assure for a good close.
I wish you the very best and enjoy your new home.
Your Realtor should have given you notice about changing brokerage firms.
Based on your information it sounds as escrow is already open so in this case it should not affect your purchase. Good luck!
I'm sorry to hear that your transaction has been so tumultuous! Every brokerage will handle your situation differently, but most will allow your escrow to finish with the previous company where your Realtor was employed. You should be okay, but it might be worth a phone call to your Realtor, their previous broker and their new broker.
I hope the end of your escrow goes smoother than the beginning!