Mage: How does HP work? No hp gain on level up?

WoW Classic
1

Hey all, I think I found a bug or I just don’t know how HP works in this game.
Essentially, I have noticed my hp was 302 at level 14, 15, 16, and now 17, despite the game telling you that you have gained 15 hp each level up. So it seemed to me that the hit point gain is bugged and shouldn’t say that and the stamina gain doesn’t matter either since I’ve gained stamina on some of those levels.

So then I try to do math to understand it, and this is where someone can help. As far as I know 1 stamina is still 10 hit points, even for a mage, even at level 14-17.
I have 27 stamina, which equates to 270 hp. That means only 32 hp is from my base hp. So I’m thinking, that can’t be right, so I ask another mage in my guild around my level. They had 25 stamina and their hp was 272. Same as me then, 32 base hp.

How does this stat work in the game? Is the level up text wrong/bugged?

2

Hrm, it seems base stamina does not equate to 10 hp per point. It only does that on buffs and gear increases.

I created a new Mage, and she had 52 hp with 20 stamina. I leveled her three times and noticed the hp did go up +15 each level like it said. Also noticed the stamina went up once and did not give any hp whatsoever for that.

So if base stamina has some sort of %effectiveness per level, does anyone have that information?