I really feel for you. Before I had my DTs, I was running a department in a challenging school, was busy, well-respected and, whilst elements of my job were hard and some weren't fun, I generally enjoyed myself. I had good friends at work, and we often went for coffee after school and so on.
Then I gave it all up to be a SAHM. It was entirely my decision, and DH and I made the necessary sacrifices in order to be able to do so. And I grew to hate it. I am a naturally outgoing and sociable person, and found being at home with two babies incredibly difficult. My only way through it was to spend a lot of time going out - for walks, to other people's houses, and so on, and even then I got fed up with the baby-talk and so on. Don't get me wrong - I love my girls to bits, and I wouldn't change my decision if I was able to go back and re-make it, but I think the thing about being a SAHM that lots of poeple experience, but no one really wants to admit, is that it changes your own perception of yourself, and that of other people - you stop being the professional, organised, well-respected person you once were, and become someone who is rushing to get a baby/akward toddler out of the house and don't realise that you have sick/banana down your back and that there is lego stuck in your hair. I know it's a cliche, but I really felt it, and I found it hard to deal with.
Once the girls got to 2 years old, we were out almost every day - music group, swimming, twins group, going to local parks and soft play, and a lot of that was just as much for me as for them - if I was able to meet up with another Mum (or two) I felt sane, and poor DH didn't end up coming home from work to verbal diarrhoea from a wife who'd not spoken to another adult all day.
When they were two and a half, I started them at a local playgroup - only £5 for 3 hours, and I could leave them there and get a couple of hours to myself - bliss. Could you do that, OP? Even a couple of mornings a week? Most playgroups aren't anywhere near as expensive as nurseries. Some days, I dropped them off and just sat in a cafe with a coffee and a magazine, which felt like such a treat!
You need to remember that you are important too. If you can't stretch to childcare during the day, try to get out in the evenings sometimes. I joined a gym, which gave me "me time". Would your DH be happy for you to have time to yourself at weekend? Even pottering around town and window shopping is good for having a break and getting a sense of yourself back.
I do think a lot of this is about being positive - don't let yourself be seen as "just" a mum. Remember that you are still the same person as you were when you were working.
Incidentally, my girls are 3 and a half now, and I have gone back to work part time. I didn't really intend to go back until they started school (this Sept) but an opportunity came up, and it felt right - it was definitely the right time for me to say that MY needs were going to come first - the twins are happy at nursery and my hours allow us to still do the swimming and ballet classes we were doing before. And I feel like more that "just" a mum again, so everyone's a winner.