Struggling with Chronic Illness: My Diagnosis and Feelings

I got diagnosed with POTS last Wednesday. I was expecting it, as I already have EDS as well. I'm glad I have a diagnosis. But I secretly hoped it would be something that wouldn't last forever. I am still trying to learn that my body needs rest. And when to take the day off. I am already in the process of trying to get SSI. But I have never felt so useless.. I feel so down. Like I'm wasting my life all because my body can't handle these things I want to do. These illnesses have been running my life. For years I worked in labor intensive environments. Being in so much pain I coped in unhealthy ways. Now all the people I love, as well as my doctors are telling me I need to rest. and focus on trying to improve my symptoms which will take a lot of time. But I'm impatient. It's slowly gotten worse, and impacted my life so much in just 5 years I can't do the things I used to. I'm scared, and I feel so alone. If you read this, thank you for letting me rant. And if you have any valuable advice it would be greatly appreciated. I'm in a very bad place mentally right now.