I always feel stronger during a full moon Donkeyman, and I know others do too.
The energy builds up as the full moon gets nearer and then it is discharged during the three day period around the full moon.
This energy is available to all who know how to access it and have the will to do so.
Wiccans/Witches.
Or of course those whose essences have the natural connection to the energy of the Universe.
US!

I cannot tell you if you are a Psi Vampire, but then you know that already.

Anything is possible though, so of course you could be, and if you are, then you could have been feeding, without realising it, on the energy of the full moon, and that could have given you the boost of energy you felt.
How long have you been manipulating energy?
What kind of energy do you use?
Have you tried Psi feeding and assessing the differences that makes to how you feel and how you work?