I'm doing it for one of my related texts for Inner Journey.
The footprints represent a journey (this can also be quite literal).
Where there is only one set of footsteps it indicates that she is taking her journey alone and may need assistance from God.
I've only just read the poem for the first time, so that's all i can give you at the moment.
I'm going to analyse it now, so i may be able to post what i wrote for my analysis.
Hope my limited information helps