Let's look at this from a different angle. Was there a time in your life where you had to suppress your emotions? Were you ever told that big girls/boys don't cry, or been criticized for being over emotional? Do you think you feel things very deeply, but internalize your emotions, or do you simply not feel anything when you know you should be having a certain emotional reaction?
I know this is a lot of questions, but often we tend to hide our feelings or deny emotional responses so much it seems like our real emotions cease to exist. Trying to bring our emotions back out where they belong is a difficult task.
When I was a few years younger than you are some things happened that were so awful that I pretty much forced myself to stop feeling anything. It was the only way I could cope. It took years to bring my normal emotions out, and some of that was very painful. I don't know if this applies to you; but you might want to find some quiet alone time and just let your thoughts and memories flow without trying to force anything. You may find some flashes of memories that explain why you feel emotionally cold now.
By the way, it took a series of Liver Flushes to help me confront and deal with a lot of anger issues that I had buried long ago. During my second Master Cleanse and a Colon Cleanse I became terribly depressed. Cleansing can bring old buried emotions out to where you must deal with them. In the long run, it has been worth the pain and effort to revive my real feelings. I used to think Mr. Spock of the old Star Trek series was my ideal, now I know an emotionless existence is very cold and lonely.