First off I think you should talk to your kid's doctor and see if there is anything you can do to help him a little more. But I don't think you should push him... not saying give up, but don't make him eat stuff that bothers him. Sometimes it helps to eat when you are feeding them, they see you eating it so they want to try it too. Kinda a monkey see monkey do thing.
My little ones love mashed potatoes, it seemed to be one of the first table foods they like to eat. But at 14 months, he is still really young & just might not be ready for the chunky foods. Other foods we gave our little ones was spagetti (cut in little pcs), mac & cheese, Lipton's rice & sauce, cereals, Gerber's Puffs, gramcracker sticks, baby cookies, and animal crackers.
I don't think I would cut back on the bottles too much until he starts eating a few more things. But most kids do switch from formula to milk around 12 mo. Some are able to switch with no problems, where others you need to mix milk and formula for awhile (start with 6 oz formula to 2 oz milk, then 4 oz formula & 4 oz milk, then 2 oz formula & 6 oz milk, then all milk - give about a week on each step).
One thing to remember is that all kids develope a bit different. So, don't always base your concerns on what others are doing.
Keep trying & good luck!