We seem to have similar problems. I can't walk very far either and the walking therefore is left to my husband. However, a few weeks ago I acquired a mobility scooter and now I can go on walks with them - great! It's something I've missed for several years as I was always out and about with our other dogs. Mollie could pull me over (even on the scooter) so my husband holds her whilst I ride alongside.
Your dogs sound lovely. We used to have a Golden Retriever that was not much bigger than a collie (I think she must have shrunk in the wash - :-)) I have to admit being a fan of big dogs. I tend to fall over small ones so a lap dog would be out for me. It's a family joke that a couple of Christmases ago I tripped over one of my daughters dogs and landed in a heap. However I still managed to keep the gateau I was carrying at the time in one piece and out of the reach of the dogs. Well, you have to get your priorities right, don't you LOL