Hello! Just wanted to add a few encouraging thots from a fellow low weight lo mommy.
My DD was also EBF. She was 50% in weight at birth and by 6 months had dropped to 5% or so and 9 mos. 3% and 18 mos 2% and now at 24 mos. she's back up to about 5. But she's perfectly happy and absolutely nothing wrong with her - just very active and not that interested in food. But a few things that helped: #1 - I had never heard of Baby Lead Weaning until I got worried about her eating and found a link on BW. Basically, we did it by default because DD simply wouldn't let me feed her - it was her way or she just would rather not eat! So she didn't do cereal or anything really - I gave her cottage cheese, avocado and I can't remember what all until she learned to use a spoon - which was quite early since she was so determined.
#2 Every once in a while after seeing a cute chubby kid at the mall I would offer DD more junk food than usual - like chocolate pudding or something just to see...and tbh she self limits on that too.
She simply wants what she wants when she wants it and that's that and there's not a whole lot I can do about it but go with the flow.
I just mean to say that if he's happy and still nursing he'll be fine. I was soooo worried for so many months and in the end it was just about getting used to food - she does not like change and avoids certain textures and doesn't like anything mixed. etc. etc.
but really it's just about giving it time.
This is a bit rambling and I don't have time to edit as DD is throwing a fit about bt. Ah well... hope there is something that helps.