I feel the same way. I think in general this is a very common problem. Just know you are not alone, by far.

Something that helped me was to avoid panic about time/ age. I was really freaked out about that for a while, and felt like the clock was ticking. Putting this kind of pressure on yourself is going to make everything difficult.

Also-

Have you been treated for your depression in the past?

For me, personally, a lot of these feelings were stemming from the fact that I was very depressed- even before I knew I was, if that makes sense. I'd try things, like you, and no matter what I did I would just feel apathetic, or worse yet, miserable and then panic for not finishing what I started. I realized that the problem really seemed to be following me around and eventually saw someone for depression. I was diagnosed clinically depressed which really would explain my lack of interest in things. And when you are generally uninterested, it is going to be very hard to figure out what you want to do with your life.

I took a break got help for it, and it felt like I remembered my ambitions again, and found true interest in new things. It really helped me pull it together. When you are depressed and anxious and stressed it is going to majorly cloud your judgement to the point where everything might seem "eh" and pointless.

This was just my personal experience with this kind of thing. I am not at all saying at all that you are depressed, but if you feel you might be, it is a thought. I felt like once I addressed that I was not fighting against myself. I remembered things that I liked, and ambitions that I had.