Hi there, Feb2000. I'm happy to help you with this.
So, there isn't such a thing as a "virgin body." People's bodies who have had a given kind of sex and people's bodies who haven't aren't different because of that experience unless someone has sustained an injury, illness or has become pregnant.
Virginity is a social construct, an idea, not something physical. Why this isn't feeling good isn't going to have anything to do with not having any kind of sex before, because there isn't a kind of sex that changes someone's body in any permanent way. It sounds like you think intercourse or other vaginal sex loosens the vagina over time: it doesn't. People can become more comfortable with that feeling, and so can learn not to do things like clench their muscles tight, but that's a thing people learn, not a physical change.
Rather, I strongly suspect it isn't feeling good for the common reasons any kind of vaginal sex doesn't: this kind of stimulation, all by itself, doesn't usually feel good to most folks with vaginas. Instead, the way more folks with this kind of body tend to feel the most pleasure is when they are more focused on other parts of their bodies, and when it comes to genitals, when they are focusing more on stimulation to their vulva, including the external portions of the clitoris. After and with that kind of stimulation -- as well as with feeling very turned on and using plenty of lube -- then vaginal stimulus can feel good, but even then, things like slow and gradual engagement with a dildo or something else, only going deeper in as it feels actually good, not painful, will tend to feel good. And for some people, vaginal sex just isn't something they enjoy at all.
I'd suggest putting the dildo away for a little bit while you instead take some time to explore masturbation that involves other parts of your body than your vagina, particularly focusing on your external genitals. You can find out more about what masturbating in this way, and in general, can look like here:
Going Solo: The Basics of Masturbation.
How does that sound to you?