[MeadowCat]

From the pictures he's looks pretty chunky to me. He doesn't have much of a tuck up and I can't see any ribs. If you can get a top down picture we can see whether he has a waist.

What and how much are you feeding him? How much exercise does he get?

 

[MeadowCat]

Six cups a day seems like a lot, even for a growing puppy. I'm not a fan of Science Diet; it has a lot of fillers and isn't great quality. If it were me, I would slowly switch to a higher quality food and lower the amount I'm feeding him. I like my dogs lean and fit, as it's much healthier for them. I like to see at least the last rib while they are moving and I want a nice tuck up and a clearly defined waist.

If you can take more pictures that would help. But I would trust your trainer and at the very least cut back on his food some.