First off, what no one ever explains until pressed is that your credit score varies considerably depending on the lending institution. I'm not talking about Transunion vs Equifax scores, etc, I'm saying that every bank has there own scoring system. So with Chase your credit score might be 650, and Wells Fargo it might be 610. It can vary as much as 100 points. Also, if they use FICO scores at all, which version of FICO are they using? I think there are 10 versions.
Also, do not trust the scores provided from these monthly credit monitoring services, they are not FICO scores and are complete fiction. According to Score Tracker, my credit score is 672; according to Wells Fargo at that same time, it was 585. No joke. I suggest not using these services at all, they are a scam in that they provide less information than what a bank sees and tend to create a a rosy picture of your credit that is not altogether accurate to entice you to sign up for their monthly service. If you need a service or some credit repair assistance and monitoring, I recommend Lexington Law. They are the market leader and get results because they persist and persist and don't give up.
My recommendation is to not worry about your credit score because you'll spin yourself into a tailwind trying to figure out who is using what. Your focus should be on cleaning up any negative items on your credit report. Period. Once that's done, your score will be fine. Also, suggest shopping around until you find a mortgage broker you like and who is willing to guide you through the process. That way you have someone in your corner who is working with you to get you approved for the best rate possible, given your circumstances.
Hope this helps and best wishes to you.