@emo245,
emo245, the reality is that the cutting could be having an effect on your body's ability to get warm/stay warm. You might not like hearing that, but sometimes the truth isn't nice. I think you already know that.
The other thing is that if you are cutting as a result of being sad/depressed, that mood could be making it difficult for your body to feel warm.
The body and mind are really closely connected.
You might find that the cutting is helping you in one way, but it's not helping you in others.
Good luck with staying warm.