A fourteen year old is a minor. A twenty year old is an adult. A fourteen year old is expected to be living with her parents and in 8th grade/high school. A twenty year old is expected to be in college with a steady job, probably living with a roommate and having minimum assistance from her parents. A twenty year old probably wouldn't be asking the questions you, as a fourteen year old, are asking.
Oral is sex, so don't say "we don't have sex" if you're going to do oral. Oral sex IS sex. It's not VAGINAL sex and it's not ANAL sex, but it IS sex. You are stupid if you want to have sex and using the word "weather" in place of "whether". Yes, anybody can get a disease, but at least a twenty year old can go to the doctor to get checked out without needing her parent/guardian to take her. That's the difference between a fourteen year old getting pleasure and a twenty year old getting pleasure. The only 100% sure way to not get an STD is abstinence. So if you're so worried he might have an STD and you don't want to be abstinent, tell him you won't blow him until he gets checked out. A twenty year old with a good head on her shoulders would require it. A respectable boyfriend that actually cares about your well-being wouldn't challenge you.