It sounds like what you want is something you don’t have where you are; so my advice is simple: you should find another place that matches your criteria. It is hard to be the only person when you are senior, much less starting out. However, while this means you may not get great design mentorship you might still find others in your company that you can learn from. One of my biggest mentors at my first job was a project manager who taught me how to pace myself. There are many professional skills to hone as a designer, and you may have some co-workers already around you that can help with them.