Sounds like my baby. Was slightly jaundiced, and weight gain was similar (though never a concern).

Ds2 still feeds 1 boob at a time, I do that as he was getting too much watery milk and not the good stuff which was giving him tummy ache. He would at times feed 3 hourly, sometimes 2 sometimes 4, and be zonked out between times, but I figure the hind milk takes more energy to digest.

I think go with what you feel is right for you and your baby. By all means try what the doc says but also trust yourself. My DS2 is now 6 weeks old and weighs 5kgs already! He was born 3.5kg as well.