I find it very significant and well written. The old situation is relevant as seeds of who Mino is, and affirms the current Mino's continuity of self. Mino dearly needs that affirmation. However the interpretation of old events is currently ambiguous.
(1) Liking some things about people or a gender isn't definitely about sexuality. Without having and analyzing relationships, many indicators of sexuality are unreliable. That includes liking boobs, a particular empathy, or even why someone crushes on their first love. Honestly IRL queer spaces that gender-typed empathy is a clearer indicator for adult sexuality than the others, even over first childhood crush's gender, but I'm not mapping that onto the story. We learned nothing truly definitive from before the changes.
(2) What someone likes now is a continuation from their earlier life, and foreshadowing. Old likes can be liked in new ways.
(3) Mino's change in likes and sexuality has precedents, and continuity, and so is not a violation of their mental self like the bodily changes. The past affirms Mino is the same person.
(4) Mino can learn to recognize this change as natural, as okay. Not as a failure, an imposition, or a wrongness to feel dysphoria about. Until then it's a source of anxiety, and adds to, as you said, embarassment.
So the details of Mino's past and current feelings, including subtext and text towards women, and heteronormative framings that can be applied male-female likes, are good continuity. We don't need confirmations. I think it's a valid read that Mino had a more complicated sexuality and naivete. It's realistic. But it's not canon or strictly relevant. What matters is this mess validates Mino's current sexuality as understandable changes and not as a massive mutation like the unwanted puberty.