I think you can really go either way at this point - whichever you feel like you want to do. There are a number of schools that expressly require two science letters, so you can either try to reconnect with an old professor or take another science class to get one, OR you can avoid applying to schools that require two science letters. Your ECs are much better than mine were when I applied.
I think you are well qualified for any DO school in the country, and if you apply broadly and realistically I think you're competitive for MD as well. I would invest in the MSAR to see at which schools you'd be competitive.