Tips for dealing with hyperventilation?

Part of the way my anxiety manifests is being convinced that I'm not breathing enough, or that I'm not getting enough oxygen even when I take huge, heaping breaths that make my ribs hurt with expanding.

Obviously this isn't great, because it contributes to alkalosis, and it's a habit I've had for a month now, so I'm doing it without even being aware of it. How can I "reset" my breathing? I feel like if I get this in order, I'll be able to deal with my actual anxiety.

You are right.  If you get your breathing under control, that will help you with the anxiety. The thing that really helped me was learning the proper breathing technique. You can find this on YouTube. There are several to choose from but there are a couple I like. One is called “mindfulness breathing guided meditation 10 minutes“ another one is called “detachment from overthinking”.    They are both very good and get you to focus on your breathing. I hope this helps! 

Hi, the most important thing I learned is to breath through your stomach and not from your lungs. Sounds weird I know but concentrate on watching your stomach expand as you breath in. Professional cyclists do this to get more oxygen into their system. Give it a go, over time it comes naturally.