Perfect! Well, not perfect that you feel like this is you. But perfect that you identified some concrete things that you can work on!
So, now, what can you do to improve these things? Ill give some thoughts...but you may know better than I do.
Confidence - Can you improve your appearance? new clothes? new haircut? improve your diet? get more sleep? - How about how you interact with people. Can you introduce yourself first? Can you go to a meetup with strangers? I think it would be best to try to find something just starting so not everyone knows each other yet. Its a lot easier than breaking into a group of established friends. - Is there something you are good at that youve stopped doing that you can restart? sewing? dancing? or something you are interested in that you can start doing? - Im sure there are some books out there about how to build confidence. Can you hit the library and get one?
Decisiveness - This may be a little trickier. But I think because you are lacking confidence, you have trouble trusting your judgment to make a decision. Im not sure exactly how to improve this. But I think if you are aware of it, you can work on yourself to try to make decisions and stick with them. How do you keep from second guessing yourself?