relationship anxiety/clinginess

I'm used to talking to someone a certain amount. So if I get no reply or I have to constantly initiate conversation one day I get mad. I know this sounds ridiculous, and I have talked to therapist about this (related to my anxiety/depression) and I'm not sure if I'm meant for a relationship at all. I know people need their space. I understand. But not when the routine suddenly changes. Do you have the same problems? And also advice for how to handle? I'm freaking 21 years old this is not how I should be acting