I agree with the above poster that the things you mention are not things that require a lot of energy. When I first read that she would not do things that require a lot of energy, I thought you were going to say she would not run around with her, chase her, play movement games, etc. I generally really prefer as low ratio care as possible for younger children, but the reason for that is because I like to see them get as much one-on-one interaction from adults as possible. It almost sounds like the opposite in your case. I would not so much worry about the lack of intellectual stimulation, but rather the lack of quality interaction. I read that you say she will still be loved, but I am not sure what kind of interactions she will be having with your dd if she does not have energy to read or do puzzles. If I were you, I would probably be looking for someone else to come to your home first. Or, talk to the nanny, tell her what you would like in terms of care for your dd and see if she is capable/willing. I have to say your in-home scenario seems pretty good as far as those goes...the ratio of 1:3 is very good for a group childcare situation.
Good luck
lucky single mom to 20 yr old dd and 17 yr old ds through 2 very different adoption routes