Touko helped Yuu with her studies

Rather, she did it because she wanted to be with her, and this was a good excuse. She did it not because it was important for Yuu to pass the exam well.

she gave her the mini-planetarium projector as a present from her trip.

Yes, this is probably the only moment. But it is not indicative, because gifts can be given to friends.

And although many of her requests start out selfish, she inadvertently helped Yuu grow as well. Joining the student council, becoming a campaign assistant, acting in the play... those are all things Yuu initially opposed, but helped her become more independant and outgoing.

And most importantly, she taught Yuu how to love.

In all these moments, she didn’t care what Yuu wanted. Even when Yuu said she didn’t want to do this, Touko insisted.
Remember the moment when she became agitated when Yuu said she was happy. She didn’t care about Yuu’s feelings, and she herself acknowledges this in Chapter 34 when she apologizes. She herself admits that she used Yuu. Is Touko so selfish that she uses a loved one instead of sacrificing her own interests for her sake?
Just for me, the word "love" = "I want all the best for you." Touko loved, but she didn’t care what a loved one feels ...
I can't remember the moment when she did for Yuu that which doesn't coincide with her interests. Whereas Yuu did this for her many times (speech, joining the student council, the play).
I can only explain this by the fact that Touko's unhealthy psyche turned her love into such an attitude.

Now you could say most of these aren't intentional, but a give and take relationship is often not direct. Yuu gets what she needs out of Touko, just like Touko does out of Yuu.

When Yuu confessed. This is the moment when she really needed a concession from Touko, so that she sacrificed her interests and at least gave Yuu a chance to love. But what did Touko do? Nothing. She didn't think she might hurt Yuu. She really didn't care about her feelings.

Now that isn't entirely true either, is it now?

Probably. It must be so. I would like to see that this is so.

I’ll enter this discussion, although I’ve always read it from afar x) (Very interesting and entertaining by the way)

I don’t think that Touko is that much horrible and selfish… She showed that she cared a few times. I would say that there are different levels concerning her "selfishness".

For the studies, she didn’t have to help Yuu. You can very well study with someone without helping them, especially if you have to review yourself. Well, it does sound awful, but it’s possible. She even offered her help later, so that Yuu doesn’t use her wish for having a good grade. It could be an excuse, but I don’t believe that it’s only that… I mean, she could find an excuse for which she didn’t have to get involved so much.

Then, I think that Touko was maybe more selfish at the beginning, because she insisted with the student council and the campaign. But at that time, she didn’t know Yuu very well, I don’t think her love was the same (it was just the beginning) and she really didn’t think about it (as if it were her only way to have Yuu more around).

I would dissociate the play from all the other stuff… Touko is a bit as if she had a "professional" side and a "personal" side. Forcing Yuu to act in the play didn't have anything to do with her feelings, because it was her purpose in life. Concerning the play, she doesn't care about others or anything. She just wants it to happen. So, she doesn't let her feelings intervene. (She almost gave up on Yuu in chapter 10, since she didn't want to help her.)

She showed a few times that she cared: she always asks Yuu if she's ok, if she's not pushing her too much, and these kinds of things. Sure it could also be viewed as selfish because "she doesn't want Yuu to hate her". I would say that Touko's level of selfishness depends on Yuu's level of kindness. I don't think we can view these two characters separated: it's all about interactions and what they allow each other. Touko would have taken less if Yuu had given less.

In chapter 34, she doesn't say that she doesn't care about Yuu's feelings (at least not for me): she says that she didn't pay attention to them, it's different. She didn't pay attention to them, because she was only focused on the idea that Yuu couldn't fall in love. Had she known that she actually could, she wouldn't have behaved the same way at all, because she would never want to hurt Yuu. If she really didn't care, she wouldn't have apologized. It would be more like "oh. Well, you're no use for me now. Go away". And she didn't make the concession right away, because she was afraid and still led by some old wound/concept she grew up with (and they are hard to get rid of).

I would think like you at some point though. Kinda. Touko is caring, but her emotional baggage weighed down on her love. That's all. Without it, I think she could be the kind that "wants all the best for her love". But most of the things that are "selfish" above are just either clumsiness, or due to her problems with Mio/her family. At least, that's my take on it!