Icons not showing on website

Hello! I’m trying to get the icons to show up in the menu for https://www.seaphoenixstudios.com, and they just show up as little boxes. I’m really pulling out my hair here. I attempted to install the Really Simple SSL plugin, but it ended up breaking my site with a too many redirects error.

I added the code found in another post to my .htaccess and that didn’t seem to work either. I’m at my wit’s end… if I can’t get them to show up, is there a way I can just use images instead?

Thanks!