It sounds to me like you're handling it well -- the one thing I might recommend is less talk during the tantrum. But if she goes to her room when you suggest it and you offer a hug and some comfort when she comes back, then you're doing well.
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I think it's important for you to remember that this is not about you -- it's about her and her development. As kids develop, they go through periods of disequilibrium where they're reorganizing their bodies, their understanding of the world, or their internal abilities. If you add hunger, tiredness, frustration, illness or something else stressful, they're going to have a very short fuse during these periods. Some kids also have a more volatile personality (like my dd). Your job is to model good self regulation (like you're doing with giving her a timeout), help her talk about her emotions when she's in a spot to talk, help her find things that regulate herself (like going to her room, hugging a stuffed animal, putting on some music), and to ride it out. But it's not your job to fix it. You can't.
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So for you, the thing to look at is: why do you find these tantrums so stressful? What's it triggering in you? How can you learn to deal with your own emotions and help her at the same time. If you've got a child prone to tantrums (and honestly, it sounds like she's pretty mild), it can be very frustrating because they're out of control and all you want them to do is stop. But this isn't something that she'll necessarily learn in a week or two - it might be months, or as in the case of our daughter, years.