If you're struggling, you could try using a suction cup dildo, mounting it on a hard floor, and then squatting over the dildo and "sitting" on it slowly.
To reach this spot, you're best using a curved dildo like the or Njoy PureWand.
A small dildo would generally be around 5 inches or less in length - don't feel the need to use all the length if you're not comfortable.