I've finished the busiest working periodtime of the year, but I am still busy and feel a bit tired. I've finished the busiest time of the year, but I am still busy and feel a bit tired.

-'busiest time of the year' is a common expression and I think it's clearer. But 'busiest working period of the year' does make it clear you're talking about your job and it isn't wrong to say it that way.

I've spent two years in themy current company, and my bosses and leaders have gradually learned to trusted me. I've spent two years in my current company, and my bosses and leaders have gradually learned to trust me.

-'my' makes it clear that this is a company you work at. -adding another verb between 'have' and 'trusted' makes it clear what the change is. You can also say 'have gradually come to trust me,' or 'have gradually decided to trust me.'

I've spent two years in themy current companyworkplace, and my bosses and leaders have gradually grown to trusted me. I've spent two years in my current workplace, and my bosses and leaders have gradually grown to trust me.

It is quite appreciated that, and I'm happy that I can show my capability and contribute to them. I quite appreciated that, and I'm happy that I can show my capability and contribute to them.

-You are the subject of the sentence so 'I quite appreciate' is clearer. Without 'it' you do need to make it clear you are talking about the last sentence, so then you add 'that.'

It is quite very much appreciated it, and I'm happy that I can show my capabilitythem how capable I am, and contribute toin them workplace. I very much appreciate it, and I'm happy that I can show them how capable I am, and contribute in the workplace.

However, I am concerned that the long working timehours erodes my privateersonal time. However, I am concerned that the long working hours erode my personal time.

-These are common expressions. The time you work is often called 'working hours' and time to yourself is often called 'personal time.'

However, I am concerned that themy long working timedays erodes my private time. However, I am concerned that my long workdays erode my private time.

I need more time to spend foron my own to relax, study, and think about my future. I need more time to spend on my own to relax, study, and think about my future.

-'for' does not go after 'to spend.' 'To spend on' is used when you are going to talk about what you are spending something on. "I spend money on food." "I spend time on myself.'

I need more time to spend for my ownself to relax, study, and think about my future. I need more time for myself to relax, study, and think about my future.

Is there anyone who feels similarthe same things? Is there anyone who feels the same thing?

-You can also say 'feels something similar.' I'm not certain how to explain it, it might just be an expression.

Is there anyone who feels similar thingsly? Is there anyone who feels similarly?