Swollen is normal. Have they told you you could eat? If they said yes then my advice would be to start. Slowly with soft foods. Try swallowing it with a bit of water or better yet something thicker. Milk? Almond milk?
I had almost half my tongue replaced and by day 8 I could eat omelets - mashed potatoes, soft veggies, soups. Everyone is different but actually moving your tongue around will help with the swelling. Move it - it gets the circulation going the swelling should go down. Don't be afraid. It took a long time for it to be "normal" but functionally okay maybe 3-4 weeks. Then they nuked me!!! Rads shrinks tissue so my tongue then got a bit smaller. Now it's Aokay. Move it around get used to it. Hugs...