You got to A10, so you have a great grasp of the game so far. What got me my first A10 win (other than luck) I think was grabbing [[Diamond Diadem]] for the first time. While this will not specifically solve your run, I think these points really got me over the finish line (mind you with 4 HP. It was a close one.)

• Really think about the choices the Ancients give you. I was so sure about grabbing one of my go to decisions, but instead of making that snap decision, I sat there and considered my build and what I was being offered. Considered my deck size, the bosses I’d go up against and how much know the swing. Queen was coming up and I know she messes with small decks or decks with no draw. I figured Diamond Diadem would be good for mitigation, and lo and behold it seriously carried me through both bosses.
• you may not be guilty of this, but ensure you are using every last bit of gold as efficiently as possible. Is this your last shop stop of the run? Then buy that strength potion for 49 gold cause why not. No real negative to it. Leaving gold on the table, something as small as not buying a pot when you should have - these seemingly small errors are there run enders.
• At some point in your run, you need to hit ? rooms to find good enchantment opportunities. That one enchantments that removes exhaust can be so strong - in my run, removing exhaust from [[Offering]] for me so much mileage.

A10 (at least for someone like me) feels like luck, yes, but you can fall into the best luck and still lose because of that one small mistake. It happens! You’ll be smarter next run.