whoa! think about the size of a full silverside in relation to that nem, then think about a sub sandwich for you in the same proportion...!!!
mine is about...10? times the size of yours, and eats about one full silverside every two days...when he was half that size, it would take him three to four days, and he would spit out half of it. i started giving him smaller pieces (half to third) and he quit spitting out the remnants. i think you're on the right track.
one thing i did think of, and it may just be the pic, is that your nem looks a little small for that clown...you would 'on average' (whatever that means) want your nem to be at least 3x the size of your clown...2" clown, 6" nem.
if you dont have that ratio, or if your clown starts to give 'extra love' you may want to help protect the nem from time to time (like with a strawberry basket or something like that over it) to give him some time to grow and/or recover. i dont think you'll have any problems, just something to watch for--and again, it may just be the angle of the pic.
anyway, great looking pair--she seems pretty happy, and that nem looks good. what kind of lights do you have?
tim