Wont open his mouth properly to eat??/ help...b4 i go mad!

My little boy is one on Thurs. He was a very good eater until lately, he was never very good with lumps when being spoon fed, preferred finger food, but now he opens his mouth just a little, preferring to suck the food from the spoon. I get so fustrated at meal times as he hardly eats much and it takes over half an hour to get such a small amount in him. I've tried giving him mini sandwiches, chips, chicken nuggets but he wont eat these either, only thing he will eat is tangerines, and half a mini yogurt???
likes crisps & organic rice cakes but he cant live on these.
He loves milk, 5/6oz when he wakes, 5-7oz bout 11ish when he has his morning sleep & 7/8oz at bedtime,
ANY advice/ideas would be really appreciated..
Marie..xx
tired.. irritated.. and wanting a holiday!!