Erectile Dysfunction? Or not?

I'm wondering if i have an erectile dysfunction. the first time i was with my recent girlfriend, i had no problem getting up. the last 3 times i would have to severely urge her to continue to stimulate me (kiss my neck, jack me off etc) because sometimes, well most of the time, she is boring and just lays there. I constantly have to coach here and I am so use to much more freaky girls. sometimes i don't get into it with here. Am i not into her? I've been kinda stressing here lately, and i do get really anxious when were about to do it. I've had this problem of going limp 2 times before with 2 different girls, but many other times I haven't had this problem. What can I do? Should i take Viagra, Cialis? is there any other medications or supplication that I can take that doesn't require a prescription?