Rob Kardashian is so out of his shell now ... he's even passing up the full service pumps during his outings with GF Blac Chyna.

Rob opted for pumping petrol himself Wednesday afternoon in Bev Hills, and did it with a huge smile. In addition to being back into the public eye, he's also back in with his family.

Yep, all signs point to Rob having a very happy 29th birthday on Thursday. Just lay off the green beer, bro ... not good for the diet.