At times I feel the same way as you. I think all of us at one point in our lives face this. You feel unfilled, dissatisfied, restless, unsettle, unhappy, disappointed, exhausted, etc. If only we always knew where we were going, and get there as quickly as possible. I have a feeling that there is a lot of behind the scene work God is doing in us that doesn't come with that feel good feeling because it hasn't bear the fruit of its labor cause we are still in the process.
Even though you don't see anything, the work being done, the seed being planted, doesn't mean that its not there. The place that you are right now, was the same place Israel was for 40 years, but even though it was a hard place, God always showed that he was there. Initially it wasn't because of their sins they were in the desert, but it was due to their sins they were in there for 40 years. Everyone must go through this, some more than others. Some of us go through it complaining, depress, restless, doubting, but these are all things that only hinder our progress. Think about those who made it to the promise land; there was only Joshua and Caleb out of hundred of thousands of people. They all went through the desert or these period of times right? But how they handled it determines how long and who got to see the promise land. Like you, I am at this period also where I feel like the biggest failure. Nothing seems to be happening, and if it does, it doesn't go right. I am not good at handling it the proper way. I am also as guilty in the way I handle it. I realize I can't do more than pray on it, and since every time I pray I get a sense of peace about it; I know that God wants me where I'm at. It doesn't mean that I don't fall back into the feeling of despair and worthlessness. But this is what the enemy wants you to focus on because he knows it will take longer to go through period if you are opposing the work that God is doing to you at this time.
You know if you plant something, you have to dig a hole, and do all sort of things to it. If the ground could feel any pain, it would feel all the pain the comes with digging the hole, and cultivating it so that the plant and seed will grow and be harvest. You and I are like the ground, we don't see what's being done, but we know its painful, uncomfortable, and unknown. Even though we don't know nor understand, we have to go though it if we want to bear fruit and be covered in beautiful flowers. As long as you continually seek God about your feelings and despairs that is all that you can do. Whether you want to suffer or not, you are still going to be in the desert. As a matter of fact you are already there. Now despite the hurt, pain, and wounds, do you try to bear with it or oppose it? The more opposition, the longer time in the desert. Sometimes many may never come out of the desert because they oppose God so much.
In a sense, I can't walk in your shoes, but I know the feeling your describing. These feelings can be suffocating this is why despite our understanding, we have to bear it and trust that God knows the why's and the how's. Our job is to pray for strength, wisdom, discernment, guidance, etc. There's no way you will be disappointed if you trust in him. This is a process that takes time. If there is another reason why you are where you are, as long as you seek God he will eventually give you an answer. It may not be immediately, but it will come.