I had that same exact response to the BFP that you did, OP. I've kept my test, because for now I can look back on it and remember very clearly the feeling of "omg I'm pregnant - yay!" I'm definitely sad that this will probably be the very last time I experience that incredible feeling.
This is my 6th pregnancy, and will hopefully be my 3rd live baby (3 miscarriages). Our kids are so far apart that it feels like a completely different experience from the others. I'm trying so hard to soak it up and enjoy every last minute. I don't want to forget how it feels, and I want to have treasured it so I can feel like it is okay to call our family complete. I am going to miss this incredible feeling of creating life, and knowing that my baby is in my belly... so much.