If you're playing with teammates from low divisions, that indicates it's low, not high? Are you getting particularly high LP (e.g. 22+) for your wins that would suggest otherwise?
The average MMR for both sides is usually pretty close to equal in any case, so if you have trash teammates, it suggest you're also up against similar trash.
Regardless, the solution is always going to simply keep playing. If your mmr is worse than you believe you actually are, then you'll win >50% of your games on average. If your mmr is above where you actually belong, you'll fall down to a level where games are fairer. You're not going to win 100% of your games regardless, so just play a lot and have faith that statistically you're more likely to face a team who feeds than be on one (provided you can reliably not feed yourself), and lets statistics do its thing.
(Keep in mind rank is meaningless for matchmaking, only mmr matters. Also keep in mind op.gg and similar just give mmr estimates, and can sometimes give almost certainly wrong estimates.)