GIRLS AND GUYS...?

okay so ive fingered my current girlfriend 5 or 6 times but ive only used 1 finger...the other day she asked if i could use 2 fingers so i said yeah...today i was her so i went to put my 2 fingers in and it didnt seem like it would fit...i mean she wasnt super tight...i just felt like i was hurting her....GIRLS ques: am i hurting her GUYs ques;Do u have to force it kinda