It is ok to say GOD bless instead of I bless .
Just another thought sometimes we hesitate to bless ourselves thinking that blessings can be taken from a higher soul or elder person. This feeling dwells in mind of some people who do not feel to bless themselves.
Divine resides within ourselves , the Universe also resides within us. So when we say I BLESS, the Divine within us is only blessing us…..
You can always do the way you love to do…