Gerardo Fernandez
Hello! I think your session might have been a little bit intense. Maybe you went too deep and forgot to breathe correctly or perhaps you were kind of tired and were about to fall asleep, something like that. Maybe all that "energy" you lost was anxiety really and when you let that go and felt relaxed it gave the impression that you lost energy?
I would recommend trying to meditate first thing in the morning or at least try different times of the day because for me the experience also depends a lot if I am tired or hungry or if I just had something to eat. Explore your meditation and find when is your best time. One thing is for sure, this can only do you good! Hope this helps a bit!
Un abrazo paisana.