Hi Meagan. Welcome to the group. That Diamond is a real nice plane! I got to fly one with a friend recently although I am training in a Skyhawk.
I was having A LOT of trouble with soft field and short field landings. One thing I finally realized is that I was waiting too late to get slow enough. Also I was somewhat afraid of being too low on final for the soft field landing. Both of these things were causing me to come in too high and/or too fast.
So I started getting slower earlier, on downwind and when starting base. That made a big difference. And for soft field landings I started coming in a little lower then I was used to seeing. That helped too.
But what steps actually helped me to get used to flyer slower, and coming in lower? Slow flight, and power off descents.