Sexual Abuse Support Group
Sexual abuse is a relative cultural term used to describe sexual relations and behavior between two or more parties which are considered criminally and/or morally offensive. Different types of sexual abuse involve: Non-consensual, forced physical sexual behavior such as rape, incest or sexual assault, or psychological forms of abuse, such as verbal sexual behavior or...

The mind has a way of protecting us and that is to block out extreme trauma. If you were drugged that could be the reason you don't remember or it could be that you have blocked out the trauma. Not being an emotional wreck is not a good measure of anything. Many people who don't remember, myself included, were not emotional wrecks. In fact, its is because we blocked it all out that we were able to live our lives and not become emotional wrecks. Then there is the other factor of not being emotionally attached to the memory just yet. For most, when memories return, they return as an image to us with no emotions attached to it. Once you start really working on your healing the feelings return. The fact that you need Lithium and Venlafaxine to keep you stable shows that you were deeply affected by this trauma so you may have blocked it out.
My advice for you would be to find a therapist who specializes in sexual assault/rape/trauma. You can heal from what happened and you deserve to heal. You deserve to live a happy life without the help of meds.