Cant tell if compulsion or necessary action

Sometimes I struggle to identify whats a compulsion and what isn't, especially with real event OCD. Im in a relatively new relationship, and a few weeks ago I was at a party and had been chatting to another girl (not flirting). Eventually this girl started trying to hold my hand so I walked away and tried to stay away. Later on in the night I fell asleep on the sofa and whilst I was sleeping she came over and cuddled up to me. I feel incredible guilt and shame as if I've cheated and I have a strong urge to tell my gf but I'm also very afraid because I feel guilty. There seems to be no obvious indication to me whether this is an OCD urge/compulsion or not. I have my first therapy session on Monday so trying to wait until then but it's driving me mad.