Conjecture is just groundless assumption. Conjecture isn't theory, hell it's below the level of even hypothesis, the foundation OF theory before peer review refines it. At least most of the biggest theories surrounding SOIAF are based off of facts, and simple connecting of the dots. Things like "One narrator said this about character Q, another narrator said that about character Q. There's a definite discrepancy between the two. One of them is lying, or both characters were not Q." Things like "We know A, B, C, D, E, F, and G about this character. This matches with this other character who also shares ALL of A, B, C, D, E, F, and G. They're either the same character, or this is a wild coincidence." Things like "This happened at X. That happened at X. Lots of stuff happened at X, so every character associated with the events of X aren't necessarily related. But the following characters WERE tied independent of X, which makes X more relevant." Those aren't mere conjectures. They're well thought-out theories. It's very telling that among all the rampant speculation that surrounds the series, when you bundle up groups of speculation that are mutually exclusive (example: ALL the speculations on who Jon Snow's mother is are mutually exclusive. If it's A, it cannot be B. If it's C, it cannot be... etc etc) it's more than telling that one of them always stands out and has more evidence/support and throughline in its formulation than any of the rest. We know a great deal about Lyanna because we can connect the obvious dots. We know for a fact that she didn't love Robert, and we have a very good idea that Robert didn't really "love" her specifically. We know for a fact that Lyanna was a rebellious girl who was said to be one of the greatest riders alive. We know she died at the Tower of Joy and we know her last words were eliciting a lifelong oath sworn from Ned that he kept to his grave. We know many FACTS about Lyanna, so basing hypotheses on those facts are more than simple conjecture. The more facts you base them off of, the more they hold up to scrutiny, the more questions they answer, the less it's simple conjecture. It's all theory, because it's unconfirmed, but that's more than just conjecture.