I still want sex but

andy5

I'm a 23 year old female and have lost all sensation during sexual intercourse but I am too embarrassed to ask a doctor about it. I haven't lost my sex drive - I still want sex but when I do have it I feel nothing.
I don't think it's a problem of 'sex gets better' because I used to love sex and now I feel nothing. I've been in a relationship for 3 years. I can't remember when exactly this started (it's been a long time now) but I think it's been happening for the past 2 years.
I just feel as though this is strange for someone in their early 20's, I always thought this only happened when you reached middle-age!
Do you have any suggestions about why this might be happening and whether this is normal? I just feel like my sex life and enjoyment of sex can't be over at 23!