Concerning your low constitution...
Haven't tested this myself so unsure if this actually is legit, but from what I've read you can counter this by temporarily increasing it (spells, potions) when your character is nearing a level up. This way (after leveling up) your character receives hit points based on his/her temporary constitution but gets to keep them once the boost vanquishes.
Remember though, this is considered cheating as it trashes the stat.
