I understand the place you are in. You are walking by feelings and negative thoughts. Those things are not Truth.
Here is some Truth for you:
John 1:12 You are God’s child
I Cor. 6:19 You have been bought with a price
2 Cor. 5:17 You are a new creation
Gal. 2:20 You are crucified with Christ, you no longer live, but Christ lives in you. He is now your life.
John 15:16 You have been chosen and appointed to bear fruit
Eph. 2:10 You are Christ’s workmanship
Phil. 4:13 You can do all things through Christ who strengthens you
I John 3:1 You are loved by God!
These scriptures are just a few of those we live by. We don’t live by feelings or what others think of us, what a day brings or what we think of ourselves. We live by what the Bible says about us and who the Bible says we are.
As far as your purpose, be faithful in the little daily things and in God’s time He will give you more. Do everything to his glory, always honoring others above yourself. That sounds simple, it isn’t. Always live as if Jesus is the next person who will enter the room.
I hope this helps. It is just a beginning.