To be honest, me too. I show them most of my messed up work. And for awhile, one of my pages was not labelled NSFW and there were breasts exposed on it.
Death Note isn't really that bad in terms of nudity, sexual or violence excessiveness. Gurren Lagann has fan service moments but Beerserk is the one that's far more mature. Now, I CAN think of some mangas I would definitely NOT show her but they are very excessive in violence, sex and gore. That's on the extreme end to the point where it wouldn't be allowed on Tapastic.
BUT ANYWAY, you're all good. Page looks great and that's SFW. When it comes to violence and blood, "excessive" gore is NSFW. That is, if you're drawing someone's intestines falling out and being stepped on or someone's brains being blown out, eye dangling by a thread, that's NSFW.
If it's sexual related, any exposure of genitals and/or breasts would be NSFW. If you have two people laying in bed together, that's fine so long as nothing is showing. And of course, any explicit sex scenes are NSFW.
Hope that....helps???
JJ