Hi @tulalulah, I am sorry to hear that you are feeling this way, I can sympathise and empathise as I feel the same, although my dynamic is slightly different and I am, I suspect, a little older than you (56)!
As @OfTheNight has said, lonliness is a taboo subject to many and probably also dismissed, by those who haven't experienced it, as a state of mind which can simply be overcome by 'volunteering', 'joining clubs', engaging in hobbies which require interaction with others, going to church or 'making an effort'. If only it were that simple! The fact that there are frequent threads on this subject on MN indicate that it is not an unusual situation, particularly for those with young children, for whom it is far from easy, I would imagine (I cannot speak with authority since I have never had children!), to find the time or opportunity to build and maintain friendships. I keep physically busy, and my mind occupied,with my hobbies, my employment, running my home, looking after my livestock etc, but, once the day is done the feeling of lonliness often comes sweeping in like a malevolent black cloud of hopelessness and angst.I use Mumsnet a good deal for vicarious and virtual friendships with other posters, primarily focusing on the subjects which interest me, having stimulating healthy debate and exchange of ideas - it helps, but is not a substitute for real friendships.
I live alone (apart from my chickens and bees), in an isolated rural location, with just one neighbour a couple of hundred yards down the lane, I also work alone and, quite literally, a whole week can pass by without me having any human contact apart from a brief conversation with a checkout operative at the supermarket or the cashier at a petrol station when I stop for fuel. I have never had a 'holiday' holiday, been abroad, been to a wedding, rarely ever get invited anywhere and it is years since I last had a meal out or indulged in any social contact. In fact, it is so long now that I fear I have forgotten how to engage in 'normal' human social intercourse and it is frightening. My birthday is coming up soon and I am dreading it - I know there will be no cards, messages or phonecalls to mark the day, nobody to share a slice of cake with, it will just be another day, but worse, since the sense of lonliness and isolation will be accentuated - Christmas is the same and I hate it! As @Billyjoearmstrong said upthread, there is nobody upon whom I could call in a crisis, or, conversely who would call me in a reverse situation. That is a very sobering thought and I am fearful that I will end up as one of those tragic cases one reads about where someone dies, is not missed and ends up being found months later as a dried up, mummified skellington! My one and only friend is someone with whom I was at college 40 odd years ago - we exchange handwritten letters three or four times a year, but she is busy with her own life and we have not met 'in the flesh' for over two years. Yes, I have aquaintances, but the fact that real friendship does not develop exacerbates the feelings I have that I am worthless, boring, dull or unloveable, compounded by the fact that I do not have, (and never will now), a family of my own and I am probably destined for a lonely old age.
I am, I know, the architect of my own situation - I am very quiet, painfully shy, very reserved, probably autistic, very ill at ease in social situations, hate pubs and crowded places and a 'wallflower' when in company. I need wide open space around me ( hence living where I do; I had to live, briefly, in a town once, through circumstance, and never in my life have I felt so hemmed in, suffocated and like a caged animal, almost literally pacing up and down, head shaking, like a Polar Bear at the zoo). I have tried joining clubs and societies, but it is not for me, I struggle to engage with people I do not know and just feel completely like a fish out of water.
I apologise for hijacking your thread to vent myself, but sometimes it helps to just let it out - especially when, ironically, there is nobody in real life with whom I can discuss it! I just do not know what the answer is, but I sincerely hope that you are able to breach the imprisoning walls of lonliness. 💐for you.