Hi, welcome to the game

Think Mave misunderstood part of your post

Your exp bar is divided into 5 sections or stages: Body, Heart, Mind, Spirit and Soul.
What you probably did was gain enough exp to fill 3 sections. Once you fill a section, your exp is locked in and you won't lose exp past the point where it would take you back to a previous section. And yes, you do get your hp and mp bar restored to full when you fill a section.