At twelve to thirteen weeks, I'm going with cockerel. Those are some very long legs and big feet for a pullet IMO. Cockerels quite commonly develop slower than pullets and would not have grown in obvious male hackle or saddle feathers yet. Although you could be hearing crowing at this age, many cockerels may not even be crowing at four months. The bright red color of his comb and wattles does not say pullet at all, and for a pullet only points towards her being ready to lay eggs, which is highly unlikely for a bird only a little over 2 months. Your birds stance is not that strange to me, it looks like normal cockerel stance and perfectly normal to look a little gangly at this teenage stage. He is one handsome bird. His posture is very regal looking.