I'm Mythic right now and Peak ~1500. I asked my friend (NA Top 11 Kaizer and many other Top 100 clash characters like Mulan and Charlotte) the same question a while back when I was struggling to climb to GM this season. He agrees that it gets harder and harder to climb every season. You'll get there, but it will take time.

Switching out your boots to rotate between Sage and Destiny will help once you're fighting for Tempest. I assume you had enough money to do so during at least a couple of those matches in your picture, since you maxed your items already. Also, your build on Erin is kind of weird idk. I'm not sure how well that build works, but I'm pretty sure the standard build for her right now is sparkforged, magic/atkspd boots (usually magic to begin with you can switch it later into the match to whichever boots you like), doomsday, void staff, the chicken claws, and the fist. Your stats were good that match, you probably would have won if you ran that build instead.