Can I add bathroom/closet in place of 2nd entry door?
Contact an local architect.  They will be able to create design drawings (and/or computer models), which will allow you to visualize the change.  This will allow you to make a more informed decision, than asking a bunch of dopes on the internet.

The architect should also be able to produce the blueprints, that can be used by a contractor to make the changes to your home.

Architects do charge for their services, but it's going to be much cheaper than building an addition you're not happy with.