[quote=@Game Maker]
[@Jinxlynx][@Zhaliora] I was taught by my DMs in all the campaigns I've played that it works as I described but if the majority of you have played otherwise (and I could have been taught wrong, some DMs do weird shit, myself included) we can do it as you have described, I just want to make sure everyone is creating their character the same way. 
[/quote]

I don't want to sound rude but who ever was DM and taught you that was how HP is calculated was majorly wrong. 
You would end up as a level 3 character with less hit points than a monster that is 1/8 combat rating. 
If you did not get more hit dice as you leveled too there is not possible way you could survive 1 round against monsters when you hit the level 10 mark and people are doing 30 damage average per round. From the way you did the math you'd have 27 hit points at level 10. A level 10 cleric can cast a spell called Harm that does 14d6 at it's lowest spell slot and do 47 damage assuming they rolled a 3 on every die.

In every edition I have played which has been 3rd, 3.5, Pathfinder, 4th and 5th it has always been either take average total per level or rolling hit dice for hp, never just taking constitution per level. It is core rules, and I know this not a typical d&d game but I just want you to understand where I am coming from, especially when my character is a Melee caster and needs those extra hit points to stick in with the other close range fighters.