Denise, I can kind of relate. I had my daughters pretty young, in a less than ideal marriage that ended when they were about 5 and 3. Being a single parent at any age is hard. Building a strong and extensive support system is so important.
Fast forward more than a few years. I never imagined having more. But, new DH didn't have children of his own; initially said he didn't want any. Until he realized how cool they were:) Along came AJ, my little midlife crisis surprise, my first PE baby. I was 37 when I delivered him, ironically, at 37 weeks! My body knew that should be it. But, like you, I really wanted a sibling close to his age. The girls love him like crazy, but they were in high school, college, and had eachother and their own lives. So, months before my 40th birthday, along came Jaden. I knew after that pregnancy, no matter what my heart said about wanting more, that was it.
Do I regret it? Of course not. If I could, would I have had the boys a little younger in life? Probably. Parenting is physically hard work. Keeping up with two very, very active little boys is tiring. I also have the career issue going on. I am at the age and point where it really needs my time and focus. And I love it and need it. I am so lucky in that DH has a somewhat seasonal career and has able to be home a lot. I honestly am not sure how I would be able to do both well without him. My parents and daughters are also very involved and much support. And, we have moved to a small community full of wonderful people- a great MOPS group and many supportive moms to be with. And, watching my two boys together, whether it be wrestling and beating eachother:) or hugging, I know it was the right choice for me. I wish you luck and peace in your decision making journey.