You could easily handle either NS or PEI - likely not both.

If you want the Bay, you could always Ferry into Yarmouth and then loop around the bay (or vice versa) back to the US. The Annapolis valley is truly lovely.

Not sure if you quite have enough time to make it to Cape Breton and still do the stuff around Fundy that you want. That and Halifax were my favourite periods of time in the Maritimes.