I have to agree with the others on this one. There is only one way to get experience, and that is, with experience. You won't get any if you don't do it. Picking and choosing what calls you go to is a terrible idea on your companies behalf because you will be getting half of what happens. To be in this field, you should have a high level of maturity and being exposed to people at their worst moments will let you realize that real quick like a slap in the face with sunburn.
That being said, not everyone should be on the ambulance. Though, their age really shouldn't be a factor. Their are people in their 40s who can't handle what is seen or goes on. You seem like you have a good head on your shoulders and you are showing maturity by wanting to discuss this matter with people by putting your neck out to the wolves.
Learn the most the can, as much as you can. Go on every call you can and learn from everything. Ask questions, your education never stops. Starting young can be really good in your case. You don't seem like an idiot who is in it for the glamor and have your name in the paper as the hero.
So yea, age can be a factor in your experience, but it truly depends on the person.