So you strop one half of the razor, up and back, and then the other half? Interesting. If the edge is flat on the strop, that should work, I think, maybe. I don't use an X stroke, I just use 1/2 an X stroke. I won't bore you with the details now.

Like Ryan said, we need to know how long you've had them for and shaved with them. For all we know you've been shaving with them for ten years :-)

I touch my razors up on a Shapton 16k about every two months or so; I've started a honing journal so I don't have to guess in the future. I rotate about six razors on and off. Ten laps on the Shapton is enough.

I wouldn't 'hold my strop very taught'. Very taught can leave too little give or flex, in my experience. Also, no pressure needed at all, you need to keep the edge touching the strop, but there's no downwards pressure when I strop. Make sure you don't twist forwards on the tang. Try and concentrate laying the blade flat, rather than any twisting forward. Make sure the strop's at the right height for you. I think a strop where it's fixed to the wall is slightly lower than the height at which you hold it works well too.

That's just all the stuff I myself think about when stropping, it's not necessarily 'right'.

EDIT: (sorry, took too long to write my post, I see you've said how many shaves! :-)