You could try Usability Testing Exchange — it's a free & open-source place where you give feedback to other people, about their websites, logos, designs, demo videos and other things, ...
... And then you get back feedback about your own work — you can link to an image, or link to a website. You get back about as much feedback as you give to others, counted in characters.
Note, though, that some people at Usability Testing Exchange are new to design and UX, maybe just like you.
(I'm developing it. The homepage mentions websites and apps, but it works equally well for images & logos.)