Another thing you can try is a security loop: Loop the tubing a bit of micro pore tape loop to skin, then if it's yanked with enough force the loop takes the force and not the cannula..
You can also just put another micro pore holding the tube down, near the cannula' just make sure you are kinking the tubing where it joins the cannula. This helps to provide some more protection from tugging..
A third thing you can do, is get some Skin tac/adhesive, which is a solution/spray that you can put on before inserting the cannula and it makes the area more sticky, and holds the cannula's securing patch better..
Talking about stickiness, do you use shower gel, moisturiser if you do, ensure that you've raised shower gel, soap etc well off the area that you'll going to put your set, and if you use moisturiser avoid using it on the area you going to be putting your set next change... As these products can effect the adhesive..
I've been pretty lucky in that 4 years of using my pump, I haven't pulled the cannula out, I do move in my sleep quite a lot and I leave my pump to roam at well..
Hope some of the above idea's help, shame to give it back if at other times you achieving good control