are my paddock boots too big?

Hi I'm pretty new too riding. I just started riding about 4 months ago and I do it every two weeks. About 2 months ago I bought SaxonEquilether paddock boots. The reviews said buy half size to size bigger because they run small( I normally wear size 10) they don't make them 10.5 either 10 or 11 so I chosed size 11. They are a bit loose I thing 10.5 would be perfect. My problem is that my feet don't stay too well in the stirups( a specially when I canter) my trainer says that I have to keep my heals more down but now i'm thinking maybe my shoes are too big.

Gabciak,

Your paddock boots may be too big, but it is unlikely that that is the reason for your feet coming out of the stirrup at the canter. It might make it a little harder for you to be really stable on the ball of your feet, though.
Usually, feet coming out of the stirrup at the canter is due to gripping up. You don't feel secure, so your grip onto the horse with your calf and knee and your heel comes up and back.
Look at the inside of your paddock boot, or half chap if that is covering your boot. Do you see an area where there is rubbbing indicated on it? Like a whiter area? If you don't ride a lot , you won't see this. If you are gripping a lot, then you tend to see this on the inside of the boot. I know that I tend to grip more with the right leg, and when I was more of a beginner, it used to cause me to lose my stirrup at the canter, every time. Over time I learned how to not grip and to keep some weight going down into the stirrup and now I don't lose them except in really unusual circumstances (like horse bucking).

So, just try to relax more at the canter, let your weight drip down into the heels. The boots might be too big, but they are not the root problem, IMO.

My feet don't get totally out of the stirrups but they don't stay on the ball( I hope I wrote this correctly) they kind move in the stirrups. Do you thing I shoud get better fit shoes or I should be fine in those. Thank you

Get some insole to take up some room and see how they feel