I think that sponsors shouldn't take on more sponsees than they can give adequate time to. Too many sponsees, and in my opinion is a disservice to all involved.
If it were me, I would sit down and voice my concerns to him before you make any decisions.
Let him know that your weekly sessions to do step work and Big Book work were/still are important to you. (I'm gathering from your post that he used to do that with you.)
If he won't, or is unable to give you the time and guidance that you need, I'd highly suggest you find another sponsor ASAP.
Don't let your recovery suffer because your current sponsor is unable to come through for you, okay?
