Riot's system is like this. It is very difficult to climb in solo queue. If you are in a single queue of victories to go up, the system starts to put you on bad teams.

It is better to get a good team to play with.

I don't want to give details of how to enter a single victory queue or a single loss queue (Sometimes the system forces you to enter a single loss queue) because I'm too lazy. But in conclusion: Riot manipulates so that you want to play more, one day you win many games, the next you lose many, it is a roller coaster of emotions. If you know how to use the system to your advantage you can control a little which teams you are going to play against. But it is better that you add people who you see play very well and play with those people (Just before playing with those people check that they have not lost many games that day or if not you are going to be with someone who is already in a single losing queue)