Lost my confidence

When I was younger I was quite been shy but over the years I built my confidence and was able to be confident and speak to groups of people and new people in recent years. There was a guy in particular who I liked but he was extremely shy and due to us both missing opportunities nothing happened.

Since this happened I have lost my confidence and struggle with dating. Before I could easily talk to a guy and flirt etc. Now I have bad thoughts that no-one wants to be with me due to my weight or lifestyle, the pressure of the media and the perfect body really does not help. Whilst there is nothing wrong with my weight I feel because that guy did not want me I feel like no-one wants me. Does anyone have any tips on how I can build up my confidence again? I can't believe I got into this situation and feel like my life is on hold.