I think you're confusing external validation with value. It might sound trite that what others think of you doesn't matter, but that is fact. They don't have to be you. Only you have to be you. William James referred to it as radical acceptance.

Let me be clear, I never feel like I've done my best at anything. I'm constantly involved in analyzing how I performed in this or that and experimenting with different outcomes to different actions. I've never felt like I handled a situation perfectly. I think I hear a lot of those same expressions from what you've said here, or something quite a lot like them.

The difference between doing your best, and being the best you is subtle, and it has little to do with uniqueness, or rather specificity of individual talents. Consider what what DaVinci would have accomplished if he felt that none of his works were worth saving. We know that he felt that none of his works were perfect expressions of his potential, but he still, nonetheless, produced and protected them. Consider what Abraham Maslow's contribution to psychology would have been had he felt (which he did at more than one point in his life) that what he had to offer had no intrinsic, permanent value.

Most fiction writers notwithstanding, there are gems that each produce that are usually left on their own desk, never to be read. Each expression is valuable, even if only in relation to the entire sojourn. Maugham's best work was also his worst in several ways.

I think, and this is only my opinion, that you need to accept the journey instead of the goal, and value yourself and your expressions in relation only to where you have been rather than where you are going, or where others seem to be.

It's all very difficult, particularly when you're male with an interdependent identity formation. I understand your pain when you express that it's hard for you to be happy when you're alone. I feel much the same way. Women are a wonderful addition and distraction. They can envelop you with their attention. While that may be bliss, it can also be stultifying. I think you need to develop a concern for and care for, not a love of, yourself before you can have a healthy relationship that is emotionally gratifying.

The distinction between care for and care about is profound. Care for implies action. Care about does not. I would suggest looking into Karen Horney and Erich Fromm's theories of personality. I suggest both because they were married at one time and their theories dovetail even though their relationship was toxic to both of them. Fromm's Humanistic Psychoanalysis may give you some clues as to how, and why, to consider your own needs, and your own products (thoughts, goals and behaviors) as both valuable and malleable.

I think you need to care for your own development so that it's easier for you to recognize it when someone cares for your development, and so that you can appropriately care for theirs as well.