Good Morning Kai,
Here is a list of techniques to start to work on and to help you get out of the anxiety and raise you self esteem. 
Use feeling-talk. You can express your personal likes and interests spontaneously rather than stating things in neutral terms, You say "I like this soup" or "I love your blouse" rather than "This soup is good," You can use the phrase "I feel" or "I think" when it is appropriate,
Talk about yourself If you do something worthwhile and interesting, you can let your friends know about it, you don't monopolize the conversation, but you can mention your accomplishments when it is appropriate.
Make greeting-talk. You are outgoing and friendly with people you want to know better. You smile brightly and sound pleased to see them, you say,” Well, Hello! How good to see you again" rather than softly mumbling "H'lo" or nodding silently or looking embarrassed.
Accept compliments. You can accept compliments graciously ("Yes, I like this shirt, too") rather than disagreeing with them ("Oh, this old thing?"). You reward rather than punish your complimenter.
Use appropriate facial talk. Your facial expressions and voice inflections convey the same feelings your words are conveying. You can look people directly in the eye when conversing with them.
Disagree mildly. When you disagree with someone, you do not pretend to agree for the sake of keeping the peace. You can convey your disagreement mildly by looking away, or grimacing, or raising eyebrows, or shaking your head, or changing the topic of conversation.
Ask for clarification. If someone gives you garbled directions, instructions, or explanations, you can ask that person to restate them more clearly. Rather than going away confused and feeling dumb, you can say, "Your directions were not clear to me. Would you please go over them again?"
Ask why. When you are asked to do something that does not seem reasonable or enjoyable, you can ask, "Why do you want me to do that?"
Express active disagreement. When you disagree with someone and feel sure of your ground, you can express your disagreement by saying things like "I have a different view of that matter. My opinion is. . ." or "I think your opinion leaves out of consideration the following factors. . ."
Speak up for your rights. You do not let others take advantage of you when you feel put upon; you can say no persistently without feeling guilty. You can demand your rights and ask to be treated with fairness and justice. You can say, "I was next in line," or "Excuse me, but you will have to leave as I have another appointment now," or "Please turn down your radio," or "You're half an hour late for our appointment." You can register your complaints firmly without blowing up.
Be persistent. If you have a legitimate complaint, you can continue to restate it despite resistance from the other party until you get satisfaction. You do not allow one or two no's to cause you to give up.
Avoid justifying every opinion. In discussion, if someone continually argues and asks you why, why, why, you can stop the questioning by refusing to go along, or by reflecting it back to the other person. You can state simply, "That's just the way I feel. Those are my values. I don't have to justify everything I say. If justifying is so important to you, you might try justifying why you're disagreeing with me so much."
Try choosing just a couple of these to start working on. choose the ones you are most comfortable with and do not worry, this takes practice. I have tried and done well and tried and failed so keep on working with us and know we care.
Gentle Hugs
Kitt