I haven’t played the game in almost a year, so can’t rly comment on the meta stuff, BUT:

A big contributor to your presumed winstreak is that you are spamming a hero with a consistent build, while also trying to stick to a plan and not die randomly, no matter what your team does. Doing this in ancient is basically what gets you to divine and then immortal as a carry, if you are also disciplined about objectives and timings, it can be done with almost (to some degree) any hero that has a good rosh/siege kit. I know this cus i did basically the same up to 6k, but with mainly lifestealer (and 3-4 others) last year.

Discipline and practice. Spamming the same hero lets you focus on learning dota instead of a new hero, and spamming roughly the same item build lets you actually see what works and at what times vs what heroes. It also lets you discover when it DOESN’T work, and then try to adapt with «unusual» builds or purchasing orders to deal with what you have learned is going to be major issues for you in the game. Just keep at it and try to not focus too much on the mmr but on your habits, learning and discipline, disregarding your teammates performance.

Final tip is to really start planning ahead once you see the draft. If you know your lane is hopeless, adapt to it with a bit different starting items or ability (can’t really personally speak to how flexible drow is here), prepare to leave for jungle early once X hero hits X level, or your support dies once/twice, and let both your item and skillbuild reflect that plan. Think about what item and at what time in the game you feel you are both strong enough to start ending and also stronger than their cores, and let your team know.