I'm just to became lvl 3, alchemy is 50, using a Novice apparatus. I do make Restore Health 4 pts x 14 secs potions, plus buyin some Potion of Healing for save-life faster recovery just in case.
That's the best I can do right now? Are you able to make instantaneous healing potions at higher/Master level?

Nope, all custom made potions will work over time. That said, when you get better and have better equipment, you will be able to make some very powerful healing potions. Feel free to buy potions now, but as you start raiding more dungeons you'll find that the game throws them at you.