Generate random numbers with specific interval

I'm trying to generate 3 numbers between 1 and 10. The interval between numbers must not be less than 2. For example: 2, 6, 9 it ok, but 2,4,7 not ok.

    private int GetGoodNumber()
{
    int lastIndex = 0;
    int x = 3;
    int randomNumber = 0;
    for (int i = 0; i < 3; i++)
    {
        int interval = UnityEngine.Random.Range(2, 7);
        do
        {
            randomNumber = interval + (UnityEngine.Random.Range(0, 10));
        } while (randomNumber > 10 || x <= 2);
        x = (lastIndex > randomNumber) ? lastIndex - randomNumber : randomNumber - lastIndex;
        lastIndex = randomNumber;
        Debug.Log(randomNumber);
    }
    return randomNumber;
}

Unfortunately, my method does not work, does anyone know the problem.