If you get hit less often or make better use of the rally mechanic, you won't need as many blood vials. Later in the game you can also gain the ability to replenish HP with viscerals or find a Hunter Tool which heals you more than Blood Vials do, with blood bullets that gives potentially 10 heals for 20 QS bullets.

Amelia is a pain in the ass without Numbing Mist, no doubt. Try to stay behind her when you can. There is an NPC summon available which may help. In general, you need to play BB a lot more aggressively than Souls. You played DS2, so you probably know that in that game it was very effective to just outspace combos and run in for a couple hits at the end? Not much of a window to do that in BB. Instead you need to learn where your enemies hitboxes won't be and attack from there, parry/backstab if possible, or exploit stagger. Or in the lategame, you cheese a lot of stuff from range with the stronger Hunter Tools or Firearms if you have a lot of bullets and high ARC or BLT respectively.

I'm pretty sure rolls were replaced with jumping while sprinting as a deliberate design choice to limit the efficacy of unlocked play and sprinting for spacing, which is really powerful in Souls games. Same reason why there's no movement penalty on locked-on play and why quickstepping has less recovery than rolling.

If you haven't tried the dungeons or pvp, you probably shouldn't be commenting on it.

Every SoulsBorne game has flaws and is overpraised but they're still some of the best games around, and frankly most of your complaints will be non-issues if/when you get better at the game. For example, eventually you should learn that trying to roll while sprinting will not give you i-frames. Then the next thing you'll realize is that there are some situations where you shouldn't be running away in the first place because this game doesn't give you an easy escape like the others. Yeah buddy, stop trying to sprint away from werewolves and shit, it's not gonna work.