There certainly can be some adjustments made to how you think about yourself. There is serious self doubt and negative self concept you have going. I am sure this is evident when people talk to you. Logically, for people who have poor self images, they present themselves in the same way they feel. Behaviorally, this would be poor eye contact, negative self statements, body language and so forth.

From your description, you seem to have overcome some earlier challenges in regards to academics. This, I am sure took some hard work and practice. The same principles could be applied to your challenges in dating. I would suggest a measured approach to this. First, practice sounding more confident when you converse with people. Eliminate negative dialogue from your vocabulary. This practice could be done through taking a speech class or going to a local Toastmasters group. Make an effort to eliminate negative dialogue, both internal(self talk) and external(what you say to others). There may be some Cognitive Distortions you are experiencing(Google that term if you need to).
Journal your experiences and review at end of the day. Again, you want to break the patterns that you have established since child hood... it will take time and patience.

Lastly, practice talking and being around members of the opposite sex. Dating services could be helpful. When you do this try not to put too much pressure on yourself by viewing a date or interaction as some big event. The more you expose yourself to these challenges, the more chance you will eventually master it. If you approach dating situations with reassuring thoughts and approach, it will go much easier.

If you are finding yourself stuck, it may be helpful to get some additional support form this. A Life Coach or therapist could be a good start in working your way past these challenges.