I agree with Mildez- your health nurse sounds out of touch. 6 months is a good place to start solids with a BF baby (and is recommended) so 7.5 months is only a breath away from that. Not sure when you first introduced solids but there is no evidence starting earlier helps them to adapt better to food.

If he is feeding well and gaining well then there is probably nothing wrong with his nutritional balance.

Gagging could just be he is not ready. Or it could, I've heard, more rarely) be linked to something like tongue tie or a higher palate. Which is manageable anyway, if he has the space to tackle food when he is ready.