I thought my youngest would never eat anything but the really liquid solid foods! She would gag and choke and start crying and then throw up everything. I even had to make her morning cereal really thin. I got worried because she was really active and the watered down foods were not providing enough calories, even with breast feeding, and she started to lose some weight.
Anyhoo, I talked to her pediatrician and he just said to keep giving her what she can eat and add some whole milk yogurt and mayo (cannola mayo if you can get it) to her diet for fats and calories. Some kids just don't get there as fast as others and the amount of weight she was losing was a little worrisome, but not earth-shattering bad. He felt if things didn't turn around by the time she turned 1 then he would start trying things like speech/feeding therapy.
Now, at almost 15 months, she feeds herself food we chop up pretty fine for her and mix with some yogurt or mayonaise and she can eat fresh fruit if it is cut up small enough...while she may be a little behind in the feeding arena, she is getting there and we never went to any therapists or anything. She is really healthy and active, so I do not worry about it anymore. She is getting her molars in, so now it is not the gagging, but the gum pain that sometimes prevents her from eating the more solid foods. we still keep some baby food around for times like that to make sure she gets something in her tummy, but now she can do the stage 3 stuff...
The moral of my story? Try not to worry about it too much and just give your son what he can eat. Every once in a while, see if he can eat something thicker...one day he might surprise you and gobble it down like it was nothing. That is what happened with my daughter!
Hope this hleps.
K.