I am not sure if it is suckering but if you look at the tip there are about 14 little black stubs and one or two purple ones, there were multiple branches coming out i had to remove. This is only about 6-8 inches of tip with that many branching there are only three branches in that area now. There were not getting sunlight and staying small so I thinned it out. It is not suckering from the dirt though.
It is two main branches, one high and one low, looking down at the middle it resembles a hors shoe, that I tied down with limbs coming off the main two, trying the espalier/japanese/step-over thing. Size wise, it is in a 7 gallon smart pot.