Take it very slow and very tiny bites & chew, chew, chew. Don't be surprized if 1 or 2 bites are all you can get in at first. Cottage cheese was much easier for me to start out with than tuna. When I did tuna, I mixed it with a lot of mustard and a tiny bitof mayo. Keeping it very moist worked best.
I will be at 7 weeks post op tomorrow and am just now starting to get my energy back. It takes time for your body to heal so baby it and allow it the time it needs. You will do great!