How to get over driving anxiety...?

I am almost 25 years old and still have not gotten a driver's license. It is so embarrassing when friends and other people want to meet up with me and I have to find a ride. I suffer from severe anxiety for many different reasons and driving is one of those triggers for me. When I was a teen, I took driver's ed and passed with flying colors, then moved out of state and was unable to get my license because of my parent's financial situation. After that time, I developed these anxieties. I am going through college now and I know I will need to be able to drive when I start my career, but I don't know how to get over this. I am extremely afraid of the interstate, semi trucks and police cars. I don't know the reasons for it, as I have never been in trouble with the law or in a serious accident. How can I get past this debilitating, crippling fear? It is effecting my life and making independence very difficult.