Me and my girlfriend had sex last night for the first time last night will she get pregnet?

We had unprotected sex but only did it for a little bit then i "pulled out" but it might of been too late i thought i might of done a lil in her but im not sure whats the chances she will get pregnet? should we take the mourning after pill? whats the side affects for her? where could i get it? im scared but shes convinced we will be fine....