It's too late when you say it's too late. Everyone is right it is up to you and no one should tell you when. I have a sister that had both of her kids before age 20...she grew up with them, sort of. They had times of living in a camper because of finances. I have other family members that waited until they were in their 30's and were more financially stable and more mature themselves thus better able to cope. I haven't had any yet, though I plan to adopt some day, and I'm 42. My aunt that raised me was 53 when I was born. She did just fine as a mother.
The issue of health and fertility is for you to discuss with your doctor. Even if I didn't desire to adopt, physically I should simply because of my health issues. Each person is different.
The most important thing to consider is are you ready because if you have a child before your ready it can cause problems that are more than physical. A good thing to do so that you can increase your ability to carry a healthy baby later on is to do what you can now to remain healthy...exercise and good diet. When you are ready to try to conceive talk to the doctor about taking folic acid.