I think just asking this shows that you have resistance, because I often do the same thing and start doubting myself. The most important thing is to have faith in yourself. The feather will come in its own time. What you shouldn't be doing is stressing about it. Desire it, feel yourself holding it in your hand, put all your positive emotions into it, convince yourself that you have it already. Do it until "Am I manifesting the feather right??" becomes "I am manifesting the feather" in your mind/thinking. Always be open to whatever happens.
Anyways.... I do the same thing, who am I to give advice? :P Hope it helps anyway!
I manifested a hair elastic when i went out for a run a while ago. I realised i needed something because it was windy!!! I decided i needed a rubber band- but i wanted one that wouldn't wreck my hair........ so...........within 50 feet-there it was-a lovely clean blue hair elastic just waiting for me! i was so blown away that i did a video on it!! I think i called it small manifestation or something like that. Don't focus so much on the feather- let the idea go and i 'll bet it will show up. Not all manifestations are immediate. Just trust they will happen in time-that's what i do!!! xxxxxxxxx