I think coolkid98's idea about asking a colleague whether you have done something right is a good one, as well as her idea about asking your manager about prioritizing your workload. In addition to asking your manager, you can try asking colleagues what they prioritize first.
I would like to know what type of job you have, as maybe if I knew that I could give you more specific tips.
I look forward to hearing back from you, and I wish you the best of luck!
