Why do i lose almost any competitive game i play?

I've just started playing competitive, although i've been playing overwatch for about 4 years, and i would say im not that bad. Now that i'm playing comp, i lost 3 games, won one, lost 4 games, won one, won 2 games and lost 4 so i lost 11/15 games, is this normal?

p.s. I only play support (as always)