I have this exact same problem, my toes aren't pointing straight out, but are more of a 45 degree angle to the horse, and I feel silly because even the little kids just learning to ride have perfect toes! I have pretty much given up as it being a conformation flaw on my part, it just doesn't feel right to have my toes facing forward, I feel like all the weight of my foot is on my little toe when they are, and actually starts hurt my knees after a while. I also can't even begin to get my toes forward at a trot or canter.
It might just be the way you are built, and I honestly wouldn't worry about it too much, having your toes facing perfectly forward is slightly overrated IMO. While I would work on getting them facing slightly more forward because you wear spurs, I wouldn't be too worried if I were you if they never face totally forward.
RH Queen O Anywhere "Sydney"
2009 Sugarbush draft