I am 27. Started post bacc last fall and got married this March while taking 13 credits, all of bio II with lab, chem II with lab, and physics II with lab. I decided to not take the August MCAT and so now it puts me at one extra year lag before I apply to med schools. For the OP, you arent old. But the longer you wait, the more you will regret it. I dont have any kids but I have to think that it must be easier going to school and not having children. But, hey, thats what the other posters here are for.
As for pursuing medicine. It hasnt been easy. I had a full time job making a salary and now have no income at all. I have had to beg, borrow, and steal to get financial aid money. I am up to the point now where I am paying out of pocket now. I have my parents paying for my car and my husband basically supporting two people. Not easy but I am glad to have family support.
Its been a tough road, even without children, I still believe that its been hard for me through all of this. Taking 6 classes is tough, especially all of them sciences. But this is really something that I wanted. After working at a hospital for 2 years, I realized this was my path and I would follow it no matter what.
At this point, god willing, if I do get into med school, I am looking at 29 years of age. I want three children, so its going to be tough but I can do it. I have gotten this far. If I can do it, anyone can. Keep up your spirits. If you really want medicine though, you need to go full steam ahead and committ to it, cause it is a very long road. And you have to be willing to get support, whether it be financial or mental, from friends, and family.