from one premie mum to another . . . .
i used to feel exactly the same after my Maternal health checks- and in hindsight these checks did me more worry than they were worth. Take Brendan to a doc that you trust and get him assessed. My twins both had tongue tie which was picked up at 8 month check. I get DS fixed as he was having an op anyway so they pinched it when he was asleep and didn't get DD done- she has no probs- if they do have to do it- its more a big deal for mum than for them - its pretty quick.
as for weight gains- my DS was below the chart - under the 10 % until he was 2 years old- at 2 1/2 he was above the 50% line and now is is heaps taller and bigger than all the kids in his class and the two grades above him - don't stress too much about the weight- he is soo close to 9kg- one crap and he is either there or below it!
As for the hole that they found- get a pead to check it- they told me that DS had a hernia- he didn't, missing a teste- he wasn't , had reflux- he didn't, and the list goes on!
i ended up down the docs after each check up b/c the health nurse was so concerned- and each time it was nothing- just normal premie stuff that will sort itself out with time. I was lucky enough to find a GP who had a premie so it was great.
HTH and just follow your gut what to think and what to discard
take care and give you bubba a big cuddle
odette