Yeah, it is not 1 to 1 in a sense lvl1 is 100-120, lvl2 121-150 etc. But having around 300 max energy is about what you need in the beginning. I think inteligence increases either how fast you get stamina levels or energy increase, so make sure you are at least lvl4, I would advise higher if you aren't discouraged from grinding for it. But "overgrinding" the start is not bad, so if you get higher levels, you will still need them later on. For example later in the game having around 2k max energy is the sweet spot for me.