It is sufficient to go to bed according to the Sunnah way and lie down as per the Sunnah. A person is neither answerable for what he does in the state of sleeping nor is it mandatory for him to keep his body only in one position or on one side. Therefore, it is not wrong if one ends up his sleeping in different positions.
Allah (Subhana Wa Ta’ala) knows Best
Darul Uloom Deoband