Painful sex

Sex always hurts me. The beginning is the worst. It is the exact same feeling I had when I lost my virginity every single time. I lost my virginity almost 3 years ago and consistently have had sex since. After the initial penetration, it doesn't hurt as bad, but after it is very painful around the opening of my vagina. Is this normal? Does anyone else experience this? It is not due to lack of lubrication or arousal. I am always plenty turned on before sex.