You shouldn't feel guilty for having sex to "check out your penis". Most people have sex just for their own pleasure. You were obviously honest with this woman about your past issues, so there was no deception.

I agree, you should be able to move on in your personal development and work on finding someone to have a relationship with...which at some point and time in the future would lead to sexual relations. You should be happy to know that it is possible to have a fulfilling relation with someone that doesn't involve sex. When that relationship develops to the point that you both want sex, you will be able to be confident that your penis is up to the task and that you have a strong emotional link to make that mechanical act of sex into a wonderful shared experience.

Good luck!