First, two friends (even new ones) interested in astrology on the dinner. Chances they don’t know each other approx birth date are small. As you said SO may or may not have mentioned my birthday. Month is more than enough to try with Cancer/Leo.
*the friend asked me if I was Cancer, but then assumed that I was on the cusp of Leo because she picked up some of the Leo/fire traits. * - cold reading, most possibly unintentional. Your subconscious reactions gave tips whether it’s Cancer or Leo, or something with Leo.
I am not on the cusp - I am in the middle of Cancer. HOWEVER, my rising sign is LEO. - so, she was wrong, but YOU found way to incorporate that info into your belief system. Confirmation bias, plain and strong.
She also picked up my ability to balance things out (libra - which is my Moon). - Barnum statement. I bet that at least 80% of population would agree if you told them that they have ability to balance things out. Then confirmation bias made YOU to pin this statement to YOUR knowledge about yourself.
Nothing that can’t be explained by well known psychological phenomena. Actually, I could pull a stunt like that easily using just knowledge from my psychological education.
This is a logical fallacy, and a failure of critical thinking. The correct question to ask is not whether there can be manufactured a provable real-world explanation for every incident whose causal provenance is as yet unknown to you. The correct question is whether or not astrology represents a reasonable, supportable option for provisionally occupying that explanatory role. And it doesn’t.
That the available evidence doesn’t yet support any explanation other than “I don’t exactly know” does not provide justification for equalizing all evidence-less options. There’s as much evidence for astrology as there is for our fates being in the hands of magical mentalist monkeys. If you’re going to put astrology on the table, I get to put the monkeys on the table next to it, because that explanation has equal weight.