Definitely call the ABA helpline. They've been amazing for me. It all sounds pretty normal, but it's so awesome to hear somebody reassuring you of that. I don't think he needs to be topped up, I think formula would just introduce more problems than it would help at this stage. Breastmilk is so much more than just food; its comfort and a painkiller too. He sounds healthy and normal to me, you're doing an awesome job.