Are you still nursing him or giving him Formula? (I don't know which you use).
For the 1st year of life, breastmilk or Formula is still a baby's PRIMARY source of nutrition, NOT solids and NOT other liquids, and they need to be fed on-demand. 24/7.
"Crackers' is probably not something he is able to 'eat' yet. Hard foods, are also choking hazards.
Does he eat ANY pureed baby food? Or minced up soft foods? It really depends on the 'size' of the foods you are giving him... at this age, still mince up or chop finely the foods for him... so that he can 'eat.'
Keep foods soft... or many babies, like pastas too.
Does your baby "chew?" Does he eat anything at all? Or nothing? Feed him whatever he will eat.
If he 'cannot' eat or chew or swallow his foods... then tell the Pediatrician. They need to know this. Some babies are also sensitive to 'texture.'
Try a variety of things.... and see what he 'likes' or what textures....
Does he still have his 'tongue-thrust' reflex? Does he push foods out of his mouth with his tongue? Or does he attempt to 'chew'?
You can feed him whatever you eat... but make it soft and mince it up.
Or some babies do not like seasoned foods. And others like it. So you have to see what your baby likes or not.
Here is a good guideline:
http://www.babycenter.com/0_age-by-age-guide-to-feeding-y...
Next, is your Pediatrician concerned about his weight/growth percentiles or not? If your Pediatrician is not worried, then you should feel fine about it. BUT, if your Pediatrician is concerned about it... he/she should have given you advice about that and what to do....
all the best,
Susan