Getting married is a big change on its own. Moving and marriage are both two of the most stressful things you do in life. To do it with stepchildren and disagreement from your family makes it even more overwhelming. So, I don't think you should be so hard on yourself.
I had a hard time when I gave up working to stay home full time. I still don't always feel like I'm as social as I'd like to be. I had a lot of luck with joining some parenting groups. Obviously you don't have newborns, which a lot of mothering groups are meant for. But, I found a good (local) parenting group through yahoo groups and a lot of those moms have kids a lot older than mine. I bet it would be a great help to meet other parents. And, I am sure there are step-parents or single moms out there that you would have something in common with. I'm assuming "mrs.fort" is a military reference. Are there parenting groups on base that you can join??
Another thing that has helped me get out in the world is volunteering. I volunteer weekly as a tutor. And, this month I started twice a month at a food pantry. The folks I've met there are really kind and friendly. idealist.org or volunteermatch.org are good places to look. Although, I bet your closest church or synagog would have some ideas--even if you're not a member.... In a pinch, you can always offer to volunteer at your stepkids' school. (so long as it doesn't send the ex into a frenzy). Schools are always in need of help. And, you would certainly meet young teachers who like kids and are up for a happy hour! (at the school I worked at we had a code word for happy hour... on Friday afternoons there would be a loud speaker announcement "Today's Optional Professional Training Program will be held at O'Ryan's immediately following dismissal..."
Lastly, I am really into environmental issues. So, I looked up some local groups in my area and signed up for some free classes that were offered. I recently took a 13 week gardening class. And, last winter I completed a 10 week environmental stewardship class. Both free. If you are into cooking, Williams Sonoma offers cooking classes at many local malls... things like that... I would just google things you are interested in and see if there is a non-profit that is in your area that is offering free training or classes that would be of interest. Worst case, maybe you can find some place to take free computer classes or something that would be a resume plus until you find work that suits you...
As far as trying to conceive...I definitely recommend being married at least 6 months to a year first. We became pregnant 4 months into our marriage, and man was that a lot to get used to all at once! Phew! So, since you have the vasectomy obstacle, you're guaranteed to have time to settle in before you TTC!
If it were our family, we would just add it to the budget or our debt snowball and start saving up for it. yardsale/craigslist stuff, mystery shop, consign clothes (i've had luck getting kids' clothes at Goodwill--they're the cheapest at only $1.25--and then selling them at consignment sales for a profit), coupon like mad, waitress, whatever. then put any extra money you have towards the reversal fund.
I've made $300 in the past two months through bank bonuses--opening checking accounts at banks where they are offering a bonus for new customers. You usually need to keep the money there for a few months to get the referral and several have minimum deposits. but, it might be an idea once you start saving money up.
Last thought--it might not be a bad idea to seek out a family counselor. You've taken a lot on! And, I've found it helpful to talk things through with an objective person. My husband and I go to a counselor every two months just for a "check up"--to make sure we're both on the same page and working towards the same goals. If things aren't going so well--a member of our family is stressing us out, there's stress at work, we're disagreeing about parenting issues, etc. we go more frequently. You don't have to go with your husband if he's not willing. But, it would still be a good idea to go on your own. You're dealing with new marital stress, stepmom stress, lack of job stress, strange ex wife drama, etc, etc. A good sounding board may be helpful. If your insurance doesn't cover counseling, I've heard that many churches offer counseling on a sliding scale or free. There may also be nonprofits that can steer you towards a counselor that helps, too. Also, social workers are licensed to provide counseling and are often cheaper than traditional psychologists.