Is it normal for your uterus to change to retroverted with no prior pregnancy at age 27?

Yes! about 20 % of women have a retroflexed or retroverted uterus. The ligaments that hold the uterus in space in the pelvis can relax or move allowing the positional changes.

Generally, the uterus, in the absence of pregnancy, retain its position. It sounds like one provider didn't describe the position of the uterus, and other noted retroversion. It has little clinical significance.