Becoming a parent is a BIG responsibility, and most 14-year-olds aren't ready for it, much less 16 year olds. (Heck, most "old mothers" who have kids in their 20's say they didn't feel ready for their children!)
Babies are expensive, consider the costs of food, diapers, clothes, doctor visits, daycare... is any job that a 14-year-old could hold going to cover all of that?
Also, if you poke holes in a condom, there goes ANY trust with the guy. Don't be surprised if he leaves you and you're denied any sort of child support because you tricked him into the pregnancy.
If you're interested in kids, why not try babysitting? That way, you can have the fun parts of having a baby, then give them back to the parents when they start screaming and getting sick!