I think the Nevada region of SCBWI often has mentorship programs, and you don't have to be in that region to apply.
My other advice is to keep working on new stuff, getting critiques, and querying. I know exactly how you feel. Around 2013 - 2015 I started getting personalized rejections, revise/resubmit requests, and then requests for more work. So many so close calls, but no offer ever made. I found a mentor through a connection at an SCBWI event. Essentially an editor who got downsized out of her job at a publisher and went into consulting for a bit. She read five of my manuscripts, we chatted on the phone a few times, I revised, she reread them, etc. Was very encouraging and even referred me to an agent. I paid quite a bit for it. And while she was helpful, those stories never got me the agent or editor contract I thought I was so close to.
About 2 years later I finally got an agent with a completely new story. I guess what I'm trying to say is there is no "magic" one thing. If you keep working at your craft and keep putting yourself out there, I believe it will happen. "Close" can mean months, maybe years, unfortunately. A lot of it is hard work, but a lot of it is also luck and serendipity, which of course the hard work and querying contributes to.
Hang in there! It does sound like you are so close. :-)