Feeling guilty if I don't donate to charity?

I feel guilty if I don't donate to charity or sign petitions for various causes. I just got two letters in the mail telling me to donate to their organizations, and now I feel bad if I don't do it. I'm also signed up for more non profit email lists than I can count, and I feel like I always have to sign their petitions, even if I'm not entirely sure I agree with a petition, then I just feel bad and sign it anyway because I support the organization in general. Should I donate to the charities I received letters from? It's not that I don't think donating to charity is a good thing, but I hate feeling guilty, and now it seems like I'd just be doing it to not feel guilty. And since I just graduated college and am unemployed, I'm trying to save my money for graduate school, etc. But that makes me sound like a horrible person, and I feel bad for not donating, and then I almost feel angry at the organizations for guilt tripping me. Is this horrible?

No, just donate what you can afford, no more. You are a good kind person. A bad person wouldn't care at all. Sleep easy.

Thank you:)

You said you sign petitions and donate money for causes you haven't read through, just to avoid feeling guilty. That guilt sounds illogical and is probably related to OCD. If I were you, I would stop donating all my money until I have clear reasons for doing so, and not just to appease emotional impulses (sounds very compulsive.) Maybe draw up a list of the most worthy causes, and then figure out how much you can afford to give to each?