First of all: Most people don’t remember everything they read or learn. Memory is not like a camcorder. We all tend to remember the things that are most relevant to what we’re doing at the time or things that we found particularly interesting or emotional. Often we remember things we think we forgot when something happens to “trigger” the memory — like someone else talking about a movie we saw long ago and haven’t thought about. When someone else starts talking about it, we then remember what we liked or didn’t like about it, too.
You already know why you are struggling. You said in your letter that you have been depressed for 6 years! That’s most of your life as a young adult in your late 20s. Depression is a real illness. It can affect your concentration and your memory. I encourage you to take a look at some of the articles on depression that are here at PsychCentral.
You didn’t mention if you have sought professional help for it. I hope so. Although depression sometimes remits spontaneously, I don’t think that it is likely to happen in your case since you’ve already been affected for so many years.
If you haven’t already done so, I hope you will see your regular physician. Sometimes there is an undiagnosed medical condition that causes symptoms similar to depression. You want to rule that out first.
If you did try some therapy and it didn’t seem to help, I hope you will give another therapist a try. Not every therapist does well with every client. You need to find someone to talk to who you trust and who you feel understands you.
If there are no therapists in your city, please see your physician for medication for the depression. Then consider joining the forum here at PsychCentral where people who are depressed talk to each other. The forums provide a place for people with similar issues to give each other support, encouragement, and advice. It is often very helpful to talk to other people who share your feelings and who have been successful in managing their depression.
You could also try doing some reading in self-help books about depression.
Please take your depression seriously and take some steps to get the help you need and deserve.
I wish you well.