I’m solo now, but have a newhire starting in May. I’ve been sole designer in past companies and there is good and bad to that situation. While there might not be internal mentors or an established process, it lends the position to be defined and developed. The opportunity is there to really make a difference with new product and establishing design language and guidelines. Another thing to consider is to pick a project or two for an outside consultancy so you can project manage as well as absorb a bit of their process.
My advice is to give it time. The bad side is they’ll work you to death and never get on board with design or your problem solving capabilities. If this happens, it might be time to start looking.