K.,
We had the same problem with our daughter. So I tried to find foods that were easy for her to mash with her gums that I also enjoyed eating. For breakfast a lot of days we would both eat cherrios with milk (hers with formula) and I would slice up small chunks of banana, or serve it with blueberries or chunked up strawberries or raspberries (make sure you gradually introduce these though because some may cause diarrhea). She also really enjoyed eating raisins, so I would cook up some rice & then at the end add raisins and serve with milk & add a little cinnamon to it. If you switch to brown rice he probably won't notice the slight difference in taste but it will get more fiber in there to help with the constipation. I would also cook oatmeal and add juice or formula and sneak in some mashed bananas or applesauce. He also might really like to drink the milk leftover from his cereal if he has one of those bowls that has a straw that goes to the bottom, my daughter loves those things. One thing that really worked was canned fruit (not exactly extremely nutritious but it is pretty soft so if he swallows a small piece without mashing it it's not a big deal). But my daughter really liked canned pears, peaches or apricots or those mixed fruit cups that are already chunked up. Also you could maybe find some soy based cottage cheese at a health foods store and put the fruit with that. If you drink a smoothie for breakfast he probably would enjoy sharing it with you even though it's pured, or if you stopped by a Jamba Juice store one day before going to the park. For lunch a lot of times I would cook up some pasta, like orzo or macaroni because they are both so small and pair it with some canned marinara sauce. Also sometimes if I was in a real hurry I would give her some Chef Boyardee Ravioli or spaghettio's because those are both pretty soft if you cut them up. I also bought some canned or frozen mixed vegetables that she could eat like green beans cut small or corn, peas or even broccoli or sliced carrots cut up really small. The more vegetables and fruits that you get him to eat the less constipation he will have, and if he was like my daughter he'll probably eat whatever you eat. If you don't like to buy canned or frozen vegetables though you could always over steam some veggies for him because then they will still be whole but will mash up really easy between his gums. For snacks I would cut grapes up into quarters or halves. I would also sometimes make potatoe salad and cut up the potatoes really small. My daughter also really liked sliced olives because we would put them on her fingers and she could just pop them in her mouth. For snacks we would also sometimes do those miniature colored marshmallows. Until my daughter had teeth I tried to stay away from meats, but sometimes she would insist so I would give her small pieces of whatever we were eating. The hard part is that the rest of the family might have to alter their diets until he gets enough teeth to really start chewing. But for dinner I would serve a lot of pasta, rice or potatoes for dinner that I cut up really small. I also gave my daughter Jello, and it was especially fun if I made it into small shapes like into the little Easter Jello Beans (I think that you can find the molds just about everywhere) because then she could kinda' pick them up herself. I also gave my daughter a popsicle sometimes while she sat on the kitchen floor, the Dreyer Whole Fruit popsicles have a whole serving of fruit in them and he'd probably really like it even though it'll make a big mess (eat it right before bath time). I think that I would find the most ideas when I went to the store by myself one evening and really slowly walked through all of the aisles. I think you would be surprised at how much stuff that you can find that he can probably mash up between his gums you just might have to cook a little more and be more a little more creative. Hope that this all helps.
S.