Feel ignored in a group and desperate for attention

Hi there! Thank you for writing such a detailed question. It takes a lot of courage to write about personal specifics, but it helped me a lot in understanding your situation better. Firstly, you may have symptoms of ADD but you do not have the disorder itself. The lack of attention/concentration and forgetfulness you have described can be present in a number of life situations or disorders.
Secondly, I am glad that you realize how far you have come in life with sheer determination and hard work. The success you have achieved does not come easily and the path is usually full of difficulties. While we work on overcoming these challenges in life, we often have to step out of our comfort zone. Each time we do that it is normal to feel shaken up, just as you did in your college life. However, when we work so hard in life to fulfill our dreams, we may not realize when these little insecurities become bigger and bigger till they start occupying most of our head space. I feel the same thing has happened to you. The inferiority complex you talked about has slowly taken root in you. It now affects the way you perceive yourself and the world around you.
Lack of confidence not only makes us doubt ourselves and our abilities, it also makes us more silent and less dynamic. We do not participate as much in discussions at work. We fear what others will think about us and thus stop speaking our mind aloud even with friends. Naturally, we get less attention from others and feel ignored, which further reinforces our reduced sense of self-worth. It is indeed a vicious cycle and the more time we spend thinking like this, the more strong our negative belief system becomes. As our self-esteem dips lower and lower, we find ourselves to be more and more unacceptable in our own eyes. Naturally, we try to cope with this, and often we try to please others around us. Unfortunately, praises and accolades from others do no good without the presence of self-love. We also start trying to be perfect in everything, as it gives us a sense of being worthy. Clearly, such unreasonable demands from ourselves (and others) is bound to fail, and in turn, makes us feel even more depressed and frustrated. Does this sound like you? If your answer is yes, then by now you must have realized that a crushed self-esteem is at the root of your problem. Depression and anxiety often lead to lack of attention/concentration and forgetfulness in day-to-day life and foggy memory in the long term.