Is it possible to make a deal with God?

Earlier this year my brother was in a really bad place mentally, to the point where I was convinced he was going to try to end his life multiple times. One morning as I was walking to school I was in tears and praying to God, begging Him for my brother’s well-being.

I told Him that it didn’t matter if I never got the life I wanted. If I had to give that up for my brother to make it out of this, I would do it.

Now at the end of the year my brother is doing much better, but I have stumbled into multiple signs that seem to tell me that I have been mistaken of my purpose this entire time, and that my idea of a happy future seemingly is not allowed to come to fruition.

Did I doom myself?