Some places do longer sleep bags that are 6-18 months, might give him more room? M&S do them and I got a tommee tippee one from boots
Next do sleeping bags that have legs and arms(more like a padded sleep suit,) which work great x
Yep same as the others we have a tog sleep suit best thing we did! He can move more freely I think he was getting frustrated with sleeping bag
Double pjs?
You can get togged sleep suits, ours are from Sainsbury’s and my baby loves them x