Can I get some advice...

So I am trying to move up in ranks. My situation is this.

Lets just start with 0 LP. I will essentially Win game after game after game until I am just at my promos or in my promos (Give or take the random loss.) Then between 89-100LP I lose nearly every game and in every game almost all lanes lose. Or someone Carries so hard they are unstoppable.

Back to 0 LP. Win my way back up to 80-100LP rinse and repeat. Don't get me wrong I'm not a good league player. this has happened to me 3 times now. Every time I drop back to the bottom I take a break from ranked for bit and play normal's.

I make a lot of mistakes, my stats are not impressive, its just a trend I notice and its frustrating.

Am I stuck? Do I just need to play more games to get a more accurate MMR? Am I a silver V and bronze I player?

If I am low Silver high Bronze then that's fine. its just working my way up the ladder, I see the door, I jiggle the handle, BAM Some kid in a darthvader mask and batman T-shirt mugs me from behind and I wake up at the bottom of the ladder, wallet gone... and I have my pants on, but my underwear is missing...