By definition uterine fibroids are in your uterus. Your uterus is well beyond your partner's reach. That thing at the top of your vagina is your cervix. The cervix has a very small hole in the middle that leads to your uterus. That hole can not be penetrated without considerable pain and trauma to you. The uterine fibroids are beyond the cervix.
If you want to make sure, feel the walls of your vagina with your fingers.