@prunemerealgood. I think this is very true and, even now, with one at primary and another at secondary, a job and an elderly mother to look out for, I am too busy for anything other than a coffee or a trip to the cinema.
The people I would confide in would be dh or my mum and, to a point, work mates. It's not v often I open up to other mums at the school, bar one or 2.
Personally, I've always found parenting environments a bit claustrophobic and a bit competitive but I know it isn't the case for everyone. Just, for some of us, the environment doesn't suit.
Op, I would follow some of the advice to see your gp. As a new mum, things like therapy are offered on a plate. You tend to have to wait more once you have an over 5. I do think you sound as if you have a bit of pnd.
As for finding people annoying and withdrawing, that could either be a sign of depression and introspection rather than a personality flaw or just that perhaps the people you're meeting aren't your cup of tea. It is better to feel that from the off, follow your instincts rather than ignore it and find later down the line, you were correct.