I've heard that the sperm can still find their way?

Hi,
Welcome to ehealthforum,
Pregnancy does not result unless semen or pre-cum has come in contact with vagina. There are no studies to prove that sperms can swim through fabrics (unless it is thin and lightly woven and there is presence of ample vaginal wetness). Wait and watch for your periods. Look out for development of any new symptoms if pregnancy is suspected. Visit your doctor/gynecologist for further evaluation and assistance if you do not get your periods within 10 days of expected period dates, or if you get abnormal bleeding. If pregnancy gets ruled out and if you are not ready for pregnancy, but intend to remain sexually active, you should consider getting started on suitable regular birth control measures to be protected (after your periods). Be regular with birth control use as instructed. Avoid having unprotected sexual contact if you are not ready for pregnancy.
Take care.