i'm no expert either but jb thinks i'm wise...
i didn't get dd weighed (having had to weigh her every two days when she was tiny and finding the whole thing very depressing) but i do know that she would lengthen and stretch before chubbing down for a while, that was her pattern of growth.
do you and dh and the baby eat together? that sometimes helps to take the pressure off, especially with finger food. and i second the idea of food in the buggy, definitely. no pressure, just a wee nibble. if he's on eggs already then dd used to love french toast buggy picnics.
the other thing is that really, at 8.5 months, he really is a teeny scrap still. i've seen plenty of people on my blog site saying that their babies really weren't ready to eat until 9 months and some later. especially bf babies, you're giving them great stuff there, not really surprising that they're not so fussed by broccoli compared to full cream milk.
it's a pain, though, about the not taking milk on the run, i wonder if you should post about that as well? i imagine he's easily distracted by this stage? (not my area, i was ffing by then). they make bfing beads to distract babies back i think, but it'd be best to ask for some help with that from someone who's been there.
good luck, anyway, try not to worry. easier said than done, but you know that stressing is counter-productive in this case.