I remember how smart i was when i graduated from high school, i knew about everything and was going to save the world! yet 5 years later after two college degrees, somehow i knew so much less about everything in life.
apparently i didn't learn enough from that lesson, b/c a decade later i went on vacation with my husband's brother and his family (3 yr old boy and baby boy). we were both APPALLED at how much TV the older kid watched (how many times can you watch Ice Age??), and how they passed the baby around to anyone who would take him.
Then WE had a baby. Once again, lesson learned. My in-laws are GOOD parents, they are highly interactive with their kids at home. That week, they were on a rare vacation w/ family they rarely see and they needed a break.
Your friend has had a totally different, (and very limited) experience with parenthood so far. And if she has an 'easy' kid, and a girl, she may never experience what you are experiencing. If you're good friends, i think it's worth sitting down with her, sans kids, and telling her that you value the friendship and her opinions, but you don't want to feel judged, and you are confident that you are doing fine, the best you can with the situation you are in. it doesn't sound like you have, but be sure you don't abandon ship w/ helping him learn to listen, sit, etc. you may need to start very small and build on the smallest of successes, but as he develops he still needs to be learning those things.
For now, it may also help to be selective about the activities & locations you meet up for. Try to pick places, times of day, and activities that will be easier for your son to be either easily entertained or (relatively) calm. IE, let him get his yayas out before you all meet up, and try to pick an activity he will like but won't get him wound up or else do something where it is appropriate for him to be very active.
Wishing you good luck and a few moments of peace :)