It's highly unlikely that sperm could get through clothing, even if the clothing gets wet with the semen that is protecting it.
Sperm is actually very fragile. It dies very quickly, and doesn't move very easily even though it has a tail. It needs semen to survive; and inside your body, it needs moisture to help propel it to the Fallopian tube where it meets the egg.
Remember though that Cowper's Gland fluid ("pre-come") can contain sperm; and although it's not as easy for pregnancy to occur, it certainly does happen.
So be sure to protect yourself from both pre-come and ejaculation by using risk reduction.
I know you are worried, and I hope this helps ease your worry. If you want to set your mind at ease, invest a few dollars in a home pregnancy kit just to prove to yourself that you're not pregnant.
I'm not surprised that you are finding sites where there is inaccurate information. I suspect they have an agenda of trying to scare you into not being sexual. However, sexual pleasure is your right, and there are many pleasurable things you can do that don't put you at risk for pregnancy or disease. So I'm glad you asked me.
And when you're ready to take the responsibility of penis-vagina sex, remember to play hot and play safe. Best of luck. Dr. J