There are many reasons why one may have memory loss. Especially if this has been going on for a few years. Please don't conclude on your own that your inability to remember things is solely due to stress. There could be a simple medical reason behind it. Certain drugs or nutritional deficiency can also lead to this problem. The stress may be a result and not a cause.
Next Steps
Please consult your GP and explain this problem. He/She may recommend some tests to check why you are having memory loss.
Health Tips
In case all your tests come clear, you may consider seeing a Psychologist.