Joss sounds all boy to me, I'm surprised by the comments that people find it girly.
Thanks everyone for your replies it makes me feel much more confident about using Joss. I feel like I need that ironed out so he is introduced as Joss since with Eliana everyone started calling her Ellie even though I didn't like it from the start. I like the suggestion of using Jasper as just a nn but I think it would be a stretch and family might just roll their eyes. I am really loving Josiah but I just don't feel like I can change Joseph. (I had a really strong dream about his name, and while normally I would write that off, this one was pretty clear that this kids wants the name Joseph :)
I realize he may just call himself Joe anyway and I will just learn to love it cause he does. Joe isn't terrible its just sounds like an older football coach kind of guy to me. Like my mother's generation rather than something a little more vintage or uncommon. I don't Eliana was supposed to go by Ella (my all time favorite girls name) and she at 2.5 calls herself "Ana" instead, go figure!
Seph is still a contender too, though I have a sister named Stephanie I have always called Steph so its a little too close for me. I am not even sure if my husband would agree to use Joss but pretty sure he likes Seph. He hates discussing baby names thus my love for nameberries
I really like Joss as a nickname for a boy ( though he will probably get "Josh?" pretty often), but I hope you wouldn't be sad if he decided to be Joe or Joseph when he grew up. I like Joseph the best out of all of your options, Jack seems boring, Jonathan is good but not as good as Joseph nn Joss, I don't like Jasper at all, and Jody seems very feminine to me. I have met a male Jody and I never got used to hearing it on a boy.