Although not a perfect solution, I’ll try and give ya some tips to hit 1800 as quickly as possible, as this is a grind I remember all too well from back in MOP, WOD, Legion, etc.
#1. For any group you consistently win games with, Btag those people immediately. LFG is designed specifically to get you to roughly 1600-1700, with the 1800+ being made from consistent play with people you do well with along the way. Do not attempt to climb all the way to 1800 with random LFG groups, or you’ll likely suffer the same frustration of time spent/points tanked that you’re dealing with now. You need consistency and synergy to get into higher ratings, and that only comes with playing with the same people (especially Healers) as often as possible. If those people aren’t online, try #2 below.
#2. Follow/get in on the Streamer Viewer RBG groups. There’s a few streamers like Teebull, UnrealisticA52, and FlarknessTV who’ve made consistent 1800-2100 groups from viewers alone, and they do this because they not only have access to past RBG Heros on alts, but also friends of friends of these people who visit their stream. A LOT of these guys just want to have fun on alts themselves, so they form semi or fully meta comps out of the gate, win consistently, rotate group members to keep MMR in check, and make it their point to get their viewers specific goals. I believe Flark has helped 500+ people get their 1600, 1800, and 2100 ratings since his stream started, though you must be prepared for constructive (and sometimes very loud) criticism.
#3. Stick to meta comps and meta specs only. Combine that with only playing during non-primetime hours. This is a frustrating one, because if your friends don’t do well with these specs, it can handicap you, but with the sheer amount of teams queueing on any given day, you should get enough games to push you to 1800. There’s a catch-22 with that however, as carry groups are more than ever before, and as they are forced to tank their MMR for sales, so too do they show up in your bracket and demoralize the group. Make sure your group understands these games aren’t the norm, and to just sweep them under the rug and re-queue. If need be, don’t play your primary games on Saturday/Sunday nights, but rather the earlier afternoons when carry groups aren’t as common.