For what it's worth, pretty much every meditative opening is followed by a contraction/restabilizing. It doesn't have to be A&P and dark night, so don't worry yourself into a self-created dark night!

That said, I do think you are keying into the kind of energies that go along with AP and sleep/dream experiences are kind of classic AP stuff. That doesn't mean that you have fully hit that stage or that the fearfulness that followed was dark night, just that you are touching it a bit.
So what you are getting is a taste of the meditative path. A heartfelt curiousity, a relaxation, an opening, a reactive contraction, and a stabilization. The heartfelt curiousity and the openings and the stabilizations are all the great stuff of meditation. Over time, there is more baseline openness and clear perception and our baseline body feeling is one of more relaxation and ease.
But then there is the contraction, the fear. Unfortunately that kinda goes with it, like a sore body and need for recovery goes with weightlifting. The mind is being rewired and that takes time. And the rewiring happens by this opening and going beyond the comfort zone and then establishing a new baseline.
A teacher can help you moderate your practice so that you have a nice balance of progress and integration. And a teacher is great to talk to when things get wierd. (But the dirty secret is most of the time they say, "can you hang in there? good.", and let the natural process continue. Or they advice reducing meditation practice intensity and encouraging walks outside, etc. to give time for the rewiring process to continue. Still it's good to have someone to talk to.)
You can also go gently and do your own exploring and maintain whatever pacing feels appropriate.
I will say, you did two great things. You are adjusting your posture, trying to cultivate a good position -- rather than ignoring your body and forcing something. That's fine! don't be one of us that wrecks our body by trying to make it do something it isn't ready for. You also drew upon your support when things were hard/wierd -- rather that walling yourself off and thinking you're damaged goods or need to be isolated from others. That's great! Don't become one of us that wallows in being a spiritual disaster and wears it as a badge of honor. Just get some help during the rough spots and remember that being a good human with good relationships is a great thing.
So, it's really your call on how to proceed. Continue being curious with practice or put everything on hold while building a support system for your practice or do a little of both.
Seems like you've been thinking about this kind of stuff for a while. It's really a natural human interest and something that can be great for our lives... if we don't get sucked into being too heroic or idealistic about the whole thing. Best wishes!