I don't have this fully worked out for myself yet, but here are some things I've been considering recently. They're not exactly novel but might be helpful nonetheless.

1) Not having runway/savings has been really quite stressful/ inconvenient at times. I think there is some amount that does just seem robustly good to have. I don't have a clear idea of exactly how much that is though. Maybe thinking through the specific scenarios that have either happened or I'm worried might happen may point me in the right direction of a figure. 

 2) I've really noticed the hedonic treadmill now that I (and my friends) earn a salary. I also expect the pressure to use money for things other than donating to only increase as I get older (more responsibilities, unexpected life events, social pressure etc.).  By donating now, at the same time as I'm trying to build up savings, I feel like I'm locking it in as part of my identity and habits, rather than waiting and trusting a future me to donate, when in the future my goals might change. 

3) For me at least, it doesn't feel like I'm only weighing up savings and donating, it feels more like I'm weighing up 
- donating (you could say ~investing in my values)
- investing financially in my future (savings)
- investing in other ways in my future (eg. getting fit, eating well, going to therapy, taking care of important relationships, trying to have experiences that help me grow and learn). 

3) There is a chance though that money is disproportionately more useful sooner for the 3rd category - eg. getting help for (mental) health issues before they get worse, acquiring skills you can then use for longer, being able to do experiments that help you make life decisions. However, the benefit of acting sooner likely applies to savings and donating too, so I'm not too sure how to weigh them up. 

4) If you're waiting to donate while you build up savings, (or invest in other ways) I'd consider having a specific set goal/plan in advance. I have a (non-EA) friend to whom saving is really important. No matter how much he saves, though, it never feels 'enough' and he keeps moving his goalpost.

5) If I really sit with it, most of the things I think I need, I really don't, but giving them all up would likely make me very sad. On the margin, however, I absolutely could (and should by my values) give more. Elliott recently wrote "Do what you can. No more. No less". I personally need to do a big sit down and think hard about where the no more, no less, truly lands me. 
 

Thank you so much for reaching out for support and advice on this. It sounds like such an emotionally hard situation, and I really hope things feel better soon for you.

If you’re currently feeling suicidal or feeling very down, I’d encourage contacting a suicide hotline and consider talking to a therapist if that’s an option available to you. Here’s an international list of helplines: https://www.iasp.info/resources/Crisis_Centres/ . 

It’s worth bearing in mind that the EA approach is about doing the most good you can with the resources you’ve got. As much as it sucks, you can’t do things with resources you don’t have. Freedom to choose what you eat is a resource that people have or don’t have, in much the same way as they may have/not have money or time.

 Additionally, while EAs often encourage having high altruistic standards, there are limits to this; it definitely shouldn’t mean taking your own life. As much as it sucks, sometimes the state of the world is that the reasonable or rational choice in a given situation means consuming animal products or things tested on animals - for example, vegans work very hard to avoid the consumption of animal products, but sometimes have to take medicine that isn’t vegan, and the vegan society endorses that:  

“The definition of veganism recognises that it is not always possible or practicable to avoid animal use in a non-vegan world. Sometimes, you may have no alternative to medication manufactured using animal products. Even if other medications are available, they may be less effective, have more side effects or be unsuitable for your healthcare needs. While it can be upsetting to compromise our vegan beliefs, we encourage vegans to look after their health and that of others, enabling them to be effective advocates for veganism.”

I can’t even begin to imagine how frustrated and upset you may be feeling. It sounds like such a difficult situation. I really do agree with the other commenters, though, about how much impact you might be able to have later on, once you have a bit more freedom. 

I’m not sure if this is helpful as an example - there may be many contextual things that feel too different, but just in case it’s helpful: I wasn't allowed to be vegan or vegetarian growing up but became vegan at university and have been mostly following a vegan diet since. I’ve convinced a lot of my friends to try vegan food and several of them have massively reduced their meat consumption as a result. Many others eat vegan when I’m around, even if they don’t normally. I’m not sure, but this may even be a thing you can do subtly now  - if it sounds possible in your context, you could try sometimes offering to cook something for your family or friends that happens to be vegan (eg. lentil dhal) and not emphasising the fact that it’s vegan. 

As other commentators have said, there are so many potential ways you might be able to help animals in future, especially with a STEM background, and I feel excited about a world where there are people so passionate about animals fighting for animal welfare. The best advice I can give based on my own experience is to focus on things you can control, and think about the future - figure out what you might want to work on, and figure out where you might want to try and build knowledge or skills to work on improving animal welfare once you can.