Your husband is really holding you back friend-wise, because he has got friends, he's just not prepared to share them or let you come along, or do something as a family. A lot of my good friends now are family friends who might have started out as my husband's friend originally (or vice versaI, but over the last decade, we've had enough bbqs and things together for me to get to know them or for him to befriend the husband. These are also the friends I would call in a crisis as I know they would help out any member of the family, not just me, say if the children needed suddenly looking after. It does sound like you don't want to challenge him about it, but the popular people I know with big friendship circles have friends that include husband/families from time to time. I find it odd you have only met one of them in 15 years, that's actually highly avoidant on his part. Do you ever socialize as a family?
I'm not a big fan of FB and would never have 400 'friends' even though I'm reasonably popular- I've found that having big groups of friends usually doesn't work for me. know you've culled them now, but it takes time and energy to keep up a profile and interact on FB, that energy could be spent asking a friendly mum from somewhere if they want to meet up.
I also think if you have the attitude you'll never chase them or ask, you will be friendless! I have had friends who are crap at maintaining contact, but do really appreciate the friendship. If you only want friends that will chase after you, you'll have fewer. Lots of people are quite shy/find it hard to ask, so just by the law of averages, if you ask a lot you meet more people. Obviously if they never reciprocate ever or seem uninterested, move on, but I've gone through phases of being resentful about this- but now am having a time when I need my friends, and I'm glad I have a good lot of people to call on in a time of crisis, even if we did have times of being very busy/little kids where we were really not in touch so much.
I just think some of the things on here about friends gossiping, being private etc, don't really do justice to what a good friend can bring in terms of support and fun and just someone caring what you do with your life.
My mum has made a lot of good friends later in life, as people do end up alone, widowed, move away, especially in groups like choirs, walking groups, MeetUp, WI, church, hobby groups and so forth. There's lots of people who would like to be friends if you want to find them. Our generation is less group oriented and has tended to very much pick and choose who it likes (so not just having friends from the local church whoever they are) and the danger then is that this falls apart quite easily when you move away/life changes. It feels more intrusive to keep asking someone over for a coffee at your house rather than going to say a choir and then having a night out based on that. Could that be a possibility?