For starters, a break is a good idea. I wish you well with your health issues. If you decide to resume hosting, you should first have a long talk with yourself and become crystal clear about what your personal boundaries are.
Advance communication is the key. Be very clear in your listing's description, your list of amenities, and most of all your house rules in order to avoid having guests show up expecting something that wasn't promised. If you're not using Instant Book (and I would recommend against it for you), you have an opportunity to ask questions of prospective guests before you agree to a booking.
A $21 per night rate (in Philadelphia, no less?) is bait for bottom feeders who will often have you practically willing to pay them to leave. Guests generally won't think more highly of your accommodations (and you) than you do. I would never accept a guest who was not fully verified. This is my second year hosting and my first year using Instant Book. Because I was in the early stages of hosting and didn't want to eliminate first time Airbnb stays, I didn't require prospective guests to have reviews. Next year I'm going to implement that requirement.
And, FYI, it doesn't matter that a dog or cat "never" goes into the room that guests stay in. Their dander floats all throughout your house and a person who is allergic will react to it. It should be stated in your listing that pets reside with you so that prospective guests can make informed choices.
Again, good luck to you.