OK at the risk of sounding pompous perhaps I can help a little.
Feeling sad for yourself is something most people do at one time or another, but many keep it private. To me, it's just an extension of feeling sad for others. Just as I reached out to give others hugs and warm words when I saw them ache, I began comforting myself when I felt sad for me. How? I'd start a little inner dialogue like,
'Awww Doug, you did your best. Don't beat yourself up, you goofy guy. Now let's go out and treat ourselves to lunch.' Trite, but I hope you understand this, as it's part of loving yourself.
As for bitter, lol, that one was easy. I simply told myself that there was no way I was going to let outside influences kill my optimism. I figured I'd always have times when I felt disheartened but refused to let it control me or my future.
As for desperate, I learned the difference between feeling that way and the feeling of intense yearning. I decided the two are actually quite different. Intense yearning inspires, desperation had me making foolish errors in judgment.
How we talk to ourselves internally and the terms-words we use is just as important as how we speak to others out loud.
Heheh, I hope some of this helps a little.