@Royalq -- I can't really give you good advice on this, but if doing too much makes you feel worthless, consider doing less. I remember deciding that I wasn't going to wear make-up or make an effort when running errands. After awhile I started to feel just as beautiful with my bare face as with my made-up face. In general, I notice that I feel more confident when I try less and when I practice non-attachment. My outlook changed a lot for the better after I started incorporating Stoicism into my life.
Another thing that I've done in the past is to make a list of all of the qualities that I admire in others, and then make another list of how I embody these qualities. This also helps me feel content. Sometimes we forget that the things we like in others are often things we like about ourselves. When you feel less than, it is often good to try to see yourself through impartial eyes. I think this list helps with that.
I also use mantras and positive self-talk. For example, I had a slow period with work, so I started to tell myself in my free moments, "I am wealthy and I am getting wealthier all the time." This is corny, but it absolutely calmed me down and gave me the space to appreciate what I had without anxiety. It also calmed me down enough so that I could formulate a plan to get more work. Of course, soon thereafter I became extremely busy. I have applied mantras to all aspects of my life, from my appearance to my relationships and I find that they almost always help.
Celebration helps me too. This ties in to my second paragraph. I think a lot of us are guilty of taking our achievements for granted. I think celebrating the good things that happen in life, esp. when you celebrate with loved ones ,can bring a great deal of contentment. You get to acknowledge in front of God and everyone the ways in which you are great and then you have the people you care about there to validate it. It can be a very, very good feeling that can carry you for awhile and help you shift your perception of yourself. Also, celebrations don't have to be limited to huge things. You can celebrate anything (you probably won't have a party for the smaller things though lol).
Being confrontational can also help in limited doses. Every once in awhile people try to speak BS into your life. They say things like, "You are [insert age] you will never get the [insert desire] you want, just accept/pick/choose something." Tell those people RETURN TO SENDER, period. Don't let that type of stuff stand unchallenged, and don't worry about being nice either. Whenever a person speaks something inaccurate or negative into your life (even if that person is you) challenge it. Don't let it stand. Pretty soon people will not feel so comfortable saying such things to you. As time goes on you can practice challenge and replace. Meaning a person says something inaccurate or negative to you, you challenge the statement and then replace it with something positive about you.
These things may or may not work for you. Others have probably already mentioned that speaking to a counselor might be helpful. There are many counselors these days who are able to advise you over the phone. Sometimes phone counseling is easier than in-person counseling. Having the phone as a barrier can help you be more candid about your feelings. I think it can be extremely hard to tell another person that you struggle with self-esteem and confidence, esp. if you look like the world should be your oyster. Also phone counseling can often be more affordable, in case you decide to go to multiple sessions.