Are my field boots too big?

I bought my first pair of field boots today. They are second hand (in very nice condition) and off aconsignment rack. The only info I have on them is that they are Ariat (zip-ups). The foot, calf are PERFECT. Not to mention they were dirt cheap. (well, 90$, compared to the 179.95$ I wouldve had to spend if I want new boots. Practically the same). One problem; they are a bit too tall (I think). The sales person said they were about 1/2 an inch too tall. Also, the ankle might be a bit too baggy, but I'm not sure. I had a suggestion to buyheel lifts for them. When I told my coach about my boot problem, she said buy them. They don't hurt the back of my knees, but they buckle a little in that area. If someone could please help, I spent all my money on these boots and can't return them. I have no idea if they will drop any more or if they are stuck like the way they are at the moment. Please help me by stating your opinion and maybe a few tricks to see if they have dropped completely. Thanks already. =)