If I interpret correctly - OP wants to convey someone didn't get the anticipated result after putting in a lot of hard work. I have framed some sentences:
1. My efforts did not provide the anticipated results.
2. I didn't get the fruits of my labour.
3. I did not reap the benefits of my efforts.
4. I did not reap the rewards of my effort
5. My hard work did not pay off.
6. My efforts did not get the desired results.
7. My efforts did not yield the expected outcomes.

**Words/ Phrases:          
Feeling undervalued,         
demotivate          
 (unappreciated, unrecognised) = efforts are not being recognised or appreciated.        
not given credit where it is due.      
achievements are not rewarded.       
Unproductive work,       
disillusioned,          
lack self-efficacy,        
underperform,