There is a difference between feeling gratitude and appreciation for something, and feeling attachment to something.
Appreciation and gratitude are states of pure love, while attachment contains fear – fear of losing or not having what you are attached to.
When it comes to something you want in your life, appreciation and gratitude attract, and attachment pushes away. If you are feeling afraid that you will not get what you want, or losing what you have, then you have attachment.
To remove the attachment, keep shifting yourself into a state of appreciation and gratitude, until you can feel that the fear has gone.