Paranoid about pregnancy, advice?

Hi all,

Recently I started seeing a guy. We’re both 18. I’m a virgin and he isn’t. I don’t plan on having sex for quite awhile and he’s fine with that, however, I’m extremely paranoid of accidentally getting pregnant. Like I said, we don’t have sex, but I do sometimes sit on his lap (fully clothed) and he’s told me precum has come out. I’m paranoid that enough would somehow get through our clothes and get me pregnant or something stupid like that. I know that’s unlikely, but I’m a very anxious person. Also, I’m not on birth control and it is not an option for me right now. Any advice or things to calm my paranoid thoughts? Thank you sex