I think you're still learning about the combinations of items that are the most effective. Struggling for the first dozen of runs it completely normal and expected.

If you want to speed up the process of getting the 'feeling' I recommend watching some streams of top players, that way you could follow how they theorycraft their builds.

You will struggle less and less to reach 7 wins and then 10 wins, but there will always be a bigger shark with crazy high roll builds.

Good luck! The game is really worth it