There's a special interest shaped hole in my life

One of the best things about autism is the special interests right? It's what motivates us to work for hours despite comorbid learning difficulties, it's what provides us with a value to employers that outweighs our weaknesses, it's what gives us our identity, happiness and purpose... and I haven't had one for years. I suffered a huge burnout and was kicked off my chemistry degree in 2013. I used to be so into it that I got 5 A*s and a place at Oxford from a bad state school with totally undiagnosed autism, dyslexia and ADHD. Since being kicked out I tried to self-study, I applied to other unis and I did Open Uni modules but the harder I tried the more demoralised I got. I've made a lot of progress obtaining diagnoses, learning study skills, managing my mental health etc. and I've decided to get a good sciencey degree so that I don't have to endure the loss of earnings, independence and intellectual stimulation that comes with staying in low-skilled work for ever. Problem is the once raging fire of interest I had is now a pile of damp ashes and nothing has come to replace it. People keep banging on about following your passions but what if you don't have any? I think it's especially important because given the difficulties I have studying and living away from home I can't just stick something out for the sake of it. On the other hand my future will be bleak if I don't have the capacity to earn higher wages and work on something vaugely rewarding, and I really do miss being immersed in science... Any words of wisdom? How can you tell if an interest has died or if it's merely been overshadowed by years of struggle? Can you rescue an interest like people rescue stale marriages?