Is it hard for a 14 year old boy to get a 14 year old girl pregnant?

Not at all. It's very easy. Just have unprotected sex and you will become parents. Probably very quickly. You are both, by the way, under the age of consent. If you think you're mature enough to have sex, you should be mature enough to take precautions. It's a simple fact of life, if you're not big enough to buy condoms, you're not big enough to use them.