Fussy eater advice

Hi everyone, I am looking for some advice. My 14 month old so. Is the fussiest eater I have ever met lol. I am really getting worried and not sure what to do. He won’t try anything new, he just pushes it away and screams if it goes anywhere near him...he doesn’t like any veg or meat....he seams to live on potatoes

List of foods he will actually eat

Porridge

Weetabix

Multigrain hoops

Toast, bread.

SWEET POTATO (his absolute favourite)

Potatoes- (waffles,chips,roast potato, and occasionally mash)

Fish (haddock,COD, salmon, tuna)

Meatballs (but only out of a tin) refuses actual meatballs

Chicken (dippers etc)

Crisps

Chocolate

Banana

Fruit purée (sachets)

Plum

Peas

Sweet corn

Pizza

Noodles, spaghetti, macaroni

Any advice on how to get him to eat other things? I have spoken to doctors /health visitors and they haven’t helped, all just say he is clearly putting on weight, so he is fine, but that doesn’t help the fact all he eats is rubbish and not healthy 😭

He is a little chunky monkey and has always been quite heavy, always moving up a clothes size 2 months before he should however this has slowed down considerably and is still fitting is 9-12 month clothes, (he started wearing them at 7 months)