Help!!! is he eating enough?properly?

[Brewster]

My baby boy is 12.5 months old and is a very fussy/picky eater.
At the moment he will eat rice krispies,
toast,
ham and cheese toasties,
custard
yogurts
elle kitchen fruit smoothies
some fruit purees
shreddies
sometimes fish fingers and baked beans
sweetcorn
rice pudding

any biscuits...

I worry so much he isnt getting enough nutrients.
He has formula twice a day and cows milk at breakfast.

He is thriving and has been walking for almost 2 months now and is a happy littel chappy usually ...

any advice?

That sounds fine to me., though I would minimise any sugary foods; they will almost always eat those in preference to healthier options. You want to encourage a wide-ranging palate, instead.