Hi, I'm New To The World Of Sexual Activity (17)

Hi, I'm new to the world of sexual activity (17) and am rather paranoid about pregnancy. My girlfriend and I have not had sex, but I have still found ways to cause anxiety. For example, after receiving a handjob, I wipe the cum off and then wash my hands and often finger my girlfriend. With this I have often feared that the sperm didn't all die when I washed my hands and then could impregnate her when I finger her. Another situation is when my girlfriend performs oral, swallows, we make out and then I perform oral on her. After swallowing, my girlfriend always washes out her mouth with an alcoholic mouthwash, but I still fear that sperm could live in her mouth, and then be transferred to my mouth when we kiss and then into her vagina when I perform oral. Am I being extremely irrational in these situations or are these reasonable reasons to be concerned about pregnancy?