I cant cum while drunk!>?!

Hi I am 18 and this is an awkward subject too talk about so i seeked out a forum

When im at parties drunk i love to Endure in the Hunt of trying to bring a girl back to my place, I live with my parents but it doesnt really phase me.

This past month ive brought 2 Girls back to my place and with one (While Drunk) i couldnt get it up at all which has happened on more then one occasion.

And with the other i got it up and we Had intercourse for an hour and a half/ Two hours, And i just lost my erection without cumming?!?

I want to know if i should seek medical help or this is just an affect of the mass amounts of alcohol i consumed.??

The second event my confidence Wasn't Effected because she was satisfied, But i still would like to climax and i would like your guys advice...

Thanks in advance