As you are already using CSJ, could I suggest that you give them a ring and tell them about this problem and see what they think? I've always found them to be really helpful - I'd expect that they would send you some samples so that you can see whether the different choices suit Bobby. As he is 5 months old now, you could think about moving him to an adult food - lots more choice there, too.
Jess cannot tolerate any wheat at all, if we walk along the canal towpath and people have been feeding the ducks then it is a nightmare, one bit of bread snaffled = runny tummy...