I think the age of consent is probably about right but does assume that children are being brought up in stable, supportive environments where sex/love/relationships are being discussed openly and honestly at home and at school. If all that takes place, I think 16 is about right. However, when that doesn't happen (as it didn't with me, DP and our friends) it's likely people will be having sex much earlier. So I don't think the issue is around the age of consent so much as cultures around sex/relationships, sex/relationship education, home environment and, more broadly, social and economic deprivation and exclusion.
When DD was in primary school, I was friends with other parents because lots of the other parents were very young too so it was fine. When DD was 7, we moved house to a nicer area and DD moved school. Then I was the youngest parent by a mile and I really struggled to fit in and make friends. There were some mums who were really nice but I always felt it was out of sympathy rather than a genuine desire to be friends. It wasn't just my age though- we moved to a "naice" area from a sink estate, we're black and most of the other parents were white so it was difficult to fit in because of those issues as well. I started letting DD walk half way home when she was about 9 so that I could avoid the school gates every day 
I did feel like I had to prove myself as a parent, yes, and I did feel quite judged. Whenever DD was a little shit I was always worried that parents would take it as confirmation that I was everything they'd imagined (i.e. useless!). I pushed DD really hard at school and I did this not only for her sake but also to protect me against judgment. It was only really when DD went to secondary school that I got out of that mindset because you're not as involved with the school then so don't meet many other parents. Apart from the one time I went to DD's secondary school for something and as I was waiting in reception in black trousers and a black coat (looked like the school uniform), a teacher sternly asked me what I was doing loitering the reception area rather than being in assembly... that made me feel pretty young 
I did make one wonderful friend at the school gates though when I'd recently moved to the nicer area. She was the grandmother of one of the other children. She was a retired lecturer, very posh and arty. She really made an effort to chat with me and I always remember her advice "take no notice of these fucking Marks and Spencer arseholes" [grinn]