NEED HELP FOR DAMAGE FORMULA WHEN USING A LITTLE HP

Hello all,
i need help about damage formula for simple attacking action.
if you ask me why i want to change the default damage formula in RPG maker VX Ace,
that's because the default parameters in RPG maker VX Ace is actually high. In level
1,HP is set at 500+. In my game, i want to set HP at 40. That's why i need to adjust actor's parameters and enemy's parameters and damage formula, so when the weakest enemy attack my player in level 1, it causes around 6-8 damage. It works perfectly at first,
the problem occurred when my player's level is gone up, in around level 4, that weakest enemy couldn't damage my player at all. If i didn't change the damage formula and just left it as the default, it actually become worse because that weakest enemy can't damage my player when his level gone to 2!!
I tried to change it so many times, but i can't erase that problem. Can someone help me? Maybe u can help me find the most suitable damage formula for a little HP.
Thank you before ;)

author=Crystalgate
I would recommend a.atk * 2 - b.def * 1. If you don't want damage to become zero if the target's defense becomes twice the attacker's attack, here's one you can try:
a.atk ** 2 / (b.def + a.atk)

Seriously though, if enemy damage goes down to zero as the player hits level 4, that's most likely because stats are growing quickly. That or you have a high defense compared to attack.

Thanks crystalgate for the answer, when i use this formula (a.atk ** 2 / (b.def + a.atk), it prevents the damage for becoming 0, but it cause the damage is only 2 when player is still level 1. Am i making any mistake in setting initial attack and defense for my player and enemy? For your information, i set my player attack at 8 and defense at 7 (but with weapon and armor equipped since beginning, it becomes 11 for attack and 8 for defense), and my weakest enemy stat's is 6 for attack and 4 for defense.

For stats growth rate, i think it one of the cause of the problems too. How is your recommendation about stats growth rate?

author=Crystalgate
I assume it's the enemy who deal 2 points of damage. My formula makes the damage rather low. You can replace it with 3 * a.atk ** 2 / (b.def + a.atk) and the enemy should deal 6-8 points of damage instead.

You gave the enemy 6 attack and the player 8 defense. With the default formula, the player is already reducing the incoming damage with 67% and once he hits 12 defense, he will take no damage. This will not happen with my formula though.

wow, thanks a lot for the formula,it helped so much.
i still have 2 questions left if u don't mind?
1. If the stats only gone up by 1 when leveling up, do you feel it's too low for a growth rate? if your answer is yes, do you have a recommendation for how it should be?
2. what's the meaning of **? i know * means multiply, but what is **?
(this question is based just from my curiosity

anyway, thanks a lot for your help, crystalgate