Yes, yes, yes. And I am embarrassed to admit it. We live in central London, and have a lovely, but small, 2 bed flat in a mansion block. Most of dd's nursery friends live in the area too. While I've only been to a few homes, ours is certainly the smallest. Many have dedicated dining rooms and playrooms, whereas we simply crowd everything into the lounge.
We were recently invited for lunch by one of dd's nursery friends. The kids dashed off to the playroom and had a ball. The mum and I sat in the kitchen/dining room area which I realised is probably half the size of our entire flat. She was perfectly nice, but found myself feeling inadequate as she talked about spending Christmas at their chalet in Courcheval (or however you spell it). She produced a gourmet quality lunch complete with extras of champagne, cheeseboard and poached pears for dessert. I enjoyed myself, but left feeling woefully inadequate. I know I should reciprocate, but somehow feel intimidated to say "come to our place (which is a quarter the size of yours) for soup and toasted cheese sandwiches". So, at the moment, I've been reduced to suggesting outings at museums, etc.
I'm not a particularly materialistic person (though I do admit to liking a few luxuries!), and hope dd has similar values, but find it hard to ignore the fact that her/our peers have so much more. I don't envy them, but admit to the insecurity of "not measuring up". Wish it didn't cross my mind, but it does, perhaps because I fear being judged by them. Pitiful, I know. So, there's my confession........