The opening parts of Axel Honneth's Freedom's Right have a pretty good overview major developments in the philosophy of freedom. He develops a typology of:

-Negative freedom from constraint
-Reflexive freedom as freedom to control one's own actions (rational control over desire, instinct, and circumstance), as well as the development of 'authenticity' (i.e. being your real self).
-social freedom - since we can constrict or empower each other's freedom, we need social institutions that reinforce freedom at the social level.

It's an academic book, so expensive, but if you have a university library you should be able to get it, or there is always LibGen. The parts that do the review are fairly short, the rest is interesting, but more a look at how Hegel's particular theory of freedom applies to our modern world.

Frankfurt's conception of "second order desires," is big in this area. This is our ability to "want to desire x," i.e. to have desires about our desires. Here is a decent summary.

https://philosophy.tamucc.edu/notes/frankfurts-theory

This ties into the biological side of autonomy when we think about how the prefrontal cortex and a "global workspace," might allow for a recursive examination of our own desires.

Last rec is a bit of a weird one. It's Wallace's Philosophical Mysticism in Plato and Hegel. This might be less helpful, but I do feel like Wallace explains his key points pretty early on and so you don't necessarily need to read the whole thing. Just search for the part where he considers Plato's Republic and the concept that "we prefer what is really good, not what we think is good."

Wallace gets at an important way in which self determination and autonomy has been defined in the history of philosophy. We become free by "going beyond," our current desires and beliefs because "we want what is really good, not what we currently think is good/true." It is in this "going beyond," that we transcend our current limits, and can thus "expand ourselves," in accordance with our reason and become more self-determining. And of course, for both Plato and Hegel, what is more self-determining and necessary is more "real," because it is less simply a "bundle of effects," a thing caused by that which is external to it.

Might not be relevant to you. I like it because it is a view of Platonism that is consistent with naturalism, and one which plays nice with science. Indeed, science is a prime example of such "going beyond," our current beliefs and desires.

I don't know what you have already read or whether this is relevant, but it's interesting:
I Am a Strange Loop
Hofstadter, Douglas R.

Parfit, Personal Identity wonderfully covers the topic from a metaphysical point of view, but it seems you're looking more for sources discussing the biological origins of one's sense of identity.

Hi and welcome to the forum. You've picked a fascinating topic! Off the top of my head some titles that come to mind:

Shakespeare: The Invention of the Human by Howard Bloom. (I'd run that one by your thesis supervisor first.)

Also Charles Taylor, Sources of the Self; Richard Sorabji, Self; Richard Carey, Augustine's Invention of the Inner Self.

Chapter II - The Biological foundations of personal identity — DeSoto

Being No One by Thomas Metzinger (or his much briefer, less technical summary The Ego Tunnel).

Also, a more general (even entertaining) treatment of the topic that comes to mind is A Dialogue on Personal Identity and Immortality by John Perry.

Have to declare an interest, in that I am in the middle of a thread on this book; nevertheless I commend to you strongly Gregory Bateson, Mind and Nature, a Necessary Unity. Herewith, a teaser:

Is there a line or sort of bag of which we can say that "inside" that line or interface is "me" and "outside" is the environment or some other person? By what right do we make these distinctions?
It is clear (though usually ignored) that the language of any an­swer to that question is not, in the end, a language of space or time. "In­side" and "outside" are not appropriate metaphors for inclusion and exclusion when we are speaking of the self.
The mind contains no things, no pigs, no people, no midwife toad s , or what have you , only ideas (ie, news of difference), in-forma­tion about "things" in quotes, always in quotes. Similarly, the mind contains no time and no space, only ideas of "time" and "space." It follows that the boundaries of the individual , if real at all , will be, not spatial boundaries, but something more like the sacks that represent sets in set theoretical diagrams or the bubbles that come out of the mouths of the characters in comic strips.
My daughter, now aged ten, had her birthday last week. The tenth birthday is an important one because it represents a breakthrough into two-digit numbers. She remarked, half serious and half in jest, that she did not "feel any different. "
The boundary between the ninth year and the tenth year was not real in the sense of being or representing a change in feeling. But one could perhaps make Venn diagrams or bubbles to classify propositions about various ages.
In addition, I want to focus on that genus of receipt of information (or call it learning) which is learning about the "self" in a way that may result in some "change" in the "self." Especially, I will look at changes in the boundaries of the self, perhaps at the discovery that there are boundaries or perhaps no center. And so on. — Ch.5.