Loss of confidence

I'm starting to have a really difficult time maintaining confidence during play. For about 15 months I've gained, every month, even if small sometimes. This month it's negative, about a 150BB swing. I play 6-max primarily.

At this point, my main problem is believing I can compete. I expect to lose. No board seems remotely safe, every card seems to make someone's 2-outer. I've reviewed a bunch of hands and mostly my play looks fine. I've managed to bet when ahead and fold when beat. The problem is I'm winning small hands and losing every single major hand. The 15BB pots never come my way, but I rake in the 4-5BB ones all the time. The exact opposite of what's desired.

As a result, I've lost my confidence in my play and my enjoyment of the game with it. Outside of just taking time off, what do people do to regain the mental mindset that they're good at poker?