Even so, we should definitely take any opportunity to create a more independent Mami. So long as her PTSD compels her to remain with her "medication", we can't be 100% sure our feelings are reciprocated, regardless of how far we push things or even if Mami takes the initiative (although I admit that's unlikely to happen while she's still in such a mindset).
I don't think you really understand. While Sabrina is effectively Mami's "medication", the
reason she is is that she's exactly what Mami needs and wants. Much like someone who just wants to be loved might develop feelings for the first person to love him/her. Hell, that's practically the basis for Homura's feelings towards Madoka. Mami most definitely isn't just going through the motions for the sake of getting a drug. Hell, even in her canon snippet, she remarks at how she and Sabrina banter back and forth like they've known each other for years. They're highly compatible people who like each other a whole lot and make one hell of a pair, not just in terms of combat and magic, but in terms of emotional and psychological needs and wants.
And by being there for Mami all of the time, we're doing more to help her eventually become independent than us trying to "wean" her off of us. It might seem paradoxical, but see my whole "child alone in the dark" analogy.
This doesn't mean that we have to throw her in the water and hope she swims, but it does mean we should talk to her about establishing a solid report with the rest of the team. In fact we should encourage the rest of the team hang out with one another outside of with us - or take note if it's already happening, which it might be.
Firstly, the word you're looking for is "rapport", or "report". Secondly, she
is establishing a solid rapport with the rest of the team. Sabrina's presence actually helps to facilitate that. The more we're around Mami, the less clingly she gets (sure, she likes the affection and physical comfort, but she doesn't feel an overwhelming need for it so long as we're there for her. Compare that to how she gets when we meet her after school each day, when she's gone hours without us, and how she desperately runs to us for comfort and relief).
To use your analogy, it's more like Mami is afraid of (bodies of) water, and us being right there beside her helps to alleviate that fear, so she comes to fear swimming less and less, until eventually she feels okay swimming on her own. By contrast, leaving her alone in the shallow end results in a terrifying experience that she comes to dread and yearns for the end of each time.
We may be the leader of the Mitakihara Quartet-hopefully-soon-to-be-Group, but that doesn't mean the relationships with us are the only ones that matter. For Mami's mental health and also for anti-micromanagement reasons. Sayaka should feel that she can not only turn to us when she feels down or needs a question answered, but also that she can contact Mami or even Homura and have them assist her with whatever she needs. And vice-versa; I'm quite sure Sayaka never expects Homura to come to her for help, so that might actually be a really good thing for her own problems, and probably for Homura to feel like she can too.
Again, I don't think you really understand what Sabrina's presence does. By being there, micromanaging becomes
less of an issue. On top of that, being there doesn't prevent others from turning to people beyond ourselves. Example: Sayaka comforting Madoka of her own initiative during our first meeting with Nadia. Or Mami coming to care for Homura on her own, being mindful of her health and things like her eating habits. Madoka, Sayaka, Homura, and Hitomi clearly care about Mami and want to help her, and that wasn't our doing.
The key thing to remember is that these kinds of bonds don't just happen because you set them up. Ironically, what you're proposing is that we do
more micromanaging. Homura is very unlikely to go to Sayaka for comfort or reassurance, because Sayaka is not someone she's used to seeing as reliable, wise, or particularly trustworthy. Homura opening up to
Sabrina is remarkable enough. That she's willing to open up at all in the
presence of Sayaka is noteworthy. Sayaka has turned to us for questions and addressing her self-doubts (as a magical girl) only once, IIRC, and that was now--and we were the only ones around, so it's not fair to say that she'd be unwilling to ask Mami about her thoughts. Hell, when we found out that Sayaka contracted, Mami reassured her entirely of her own volition.
And relationships with Sabrina
aren't the only ones that matter. We've seen this time and time again. Homura actually sees Mami as a dependable ally. She also sees Sayaka as useful, which is a very far cry from how she usually sees Sayaka as a doomed anchor to drag everyone down around her. Mami clearly cares about Homura's well-being, and would be there in a heartbeat for Homura if she gave any indication of feeling down or distressed. Madoka and Sayaka (and Hitomi) continually show concern and care for Mami. Kyouko's relationship with Yuma is having tremendous positive effects on the both of them, and that's been pretty much entirely independent of our efforts. Sayaka is shaping up to be a friend for Kyouko and Yuma, too. Mami is definitely becoming more sympathetic towards Kirika and Oriko. Homura and Madoka are becoming closer to each other and more comfortable around each other. Sayaka looks up to Homura and likes her as a person. All of this is happening naturally. I don't think there's any need to try and force it.
Maybe we should bring it up with Mami, or even the whole group, once the conversation lulls. Even Hitomi and Madoka can assist with this - for one, they have the ability to give 100% in school because they don't have to worry about training for combat. Not to mention more brains means more opportunity for a Eureka Moment which could lead to a cool new idea.
Perhaps we could try something like that in the more distant future, but for now, it feels too...forced. And definitely too much like micromanagement.
