First of all, I think there are probably better addresses to bring your questions to than this forum, where you’d find higher quality responses, which you deserve to hear.
That said, I will take a stab at it, because I wonder if your interest goes beyond just time bound mitzvos, as yr second question is leading there…
The first question induces a corollary question – if women are exempt from time-bound mitzvos because they need to care for children, why would girls or women who aren’t mothers of children be included? Perhaps a more nuanced reflection on women and their nature is implied.
If you acknowledge that women and men are – ba’gadol – different (acknowledging that all women have some “masculine” energies and vice versa), that is still within a large spectrum of difference. We all know women who are more logical and analytical, and could probably learn gemara better than some men, but the reality is that most women do not relish a purely abstract mental avodah – if it’s not tied to SOMETHING, it is just annoying. Men, in general, have a much greater tolerance for the ungrounded pure pilpul that is necessary for real gemara learning. (No question that some men have a greater need for “bringing it down” than others – but for real Talmud Torah, the machshava requires a lot of purely theoretical shteiging. )
Al pi Torah hashkafa, the superpower of women is to take the input from the mashpia, and bring it down into the world of Asiya – not just in the physical realm, but even in the realm of thought – women can smell the implications for a certain line of thinking in terms of chinuch or social endeavors much quicker than men – in general. (No way to have this discussion without some generalizing, so just will say it once and assume that every generalization has its exception.)
As a woman who happens to have a pretty strong analytical capacity (got 95% on my LSATs), I see how empowering this superpower is – consider the verses of Ayshes Chayil – that is my vision for Jewish femininity – and I see why time bound mitzvos would tie down and inhibit my impact.
(A good question you should ask is why do men need time-bound mitzvos? Lots of hashkafa on that topic, but the obvious implication is that the same koach to go all analytical requires these anchors to stay firmly attached to the ground.)
Forgive me if I read between the lines something you aren’t saying, and that might not be there, but it seems that you are equating the external role of these mitzvos and the way we, as a society, relate to them, as being somehow more “choshuv” than what women are doing.
By definition, a girl who is bas mitzvaed, should have the same hargasha that she has entered a new level, and feel the gravitas of that new stage. But socially – depending on what community you are in – the celebration of this new level may be very minimized, and that is perhaps too bad for some girls, like yourself that feel “less than” because of it.
But even bar mitzva celebrations for boys are totally different between communities, and in some communities, it’s not the big extravaganza that it is in others. So you have to distinguish Torah hashkafa from the hanhagos of different communities.
Know that within your role as a young woman, you can achieve tremendous accomplishments in your avodas H’ and become an “Isha chashuva” , even without the time-bound mitzvos.
Although if there is something specific you’d like to do, ask a rav — there are many women that have taken upon themselves mitzvos like davening maariv or shaking lulav and esrog to enhance their avoda. Certainly there we all have to “personalize” our avodas H’, if we want to be the best Jews we can be. No one can really just rely on what everyone else is doing if they want to actualize their full potential.
You sound like a thoughtful person with big kochos – and you may have some needs that lie outside the typical, but you still wholesome and Torah-true ways to fulfill them. Don’t give up on asking questions and searching for emesdich answers!
Two good sources on feminine vs masculine roles are the book by Miriam Kosman, Circle, Arrow, Spiral, and the classes of Tamar Tabak online. Both ladies have done their research and offer many sources you may find encouraging to appreciate your role as a Jewish woman. Hatzlacha and a sweet year to you!