Sounds like it was your period. Those 'strings' and little balls of blood are blood clots. When you have your period, the lining of your uterus is shedding. It can appear stringy and there can be blood clots.

If you are going to engage in risky sexual experiences (ie, unprotected sex), please invest in some condoms. They give them away for free at Planned Parenthood and they cost much less than a package of diapers do if you buy them at the drugstore.

First some preaching: NEVER allow a penis without a condom close to your vagina unless you are willing to become a mommy. It is your choice and you should insist on it.

It sounds pretty much like you had your period which means you are not pregnant. Only you will know if that was your period though as you know what it is normally like for you. Did your period arrive when you expected it?

PLEASE take care in future!!