Don't count buttons. Buttons have nothing to do with it. Look in a full-length mirror and assess what, in coordination with your build and everything else you are wearing, looks balanced and aesthetically appealling to your eye.Question regarding the shape of the V. Classic sweaters often had deep V's. Not so much now but they seem to be coming back in popularity
You probably wouldn't want too shallow of a "V" because that could make you look like your sweater is too small. Too deep a "V" and it could look too big. But the terms "shallow" and "deep" are relative. Go with what you like and what looks good on your frame.
Of course, if you are seriously concerned about having too deep a "V," you can eliminate your dilemma completely-simply forego the V-neck and wear a Z-neck sweater instead. The Z-neck: it's the next big thing in menswear. It's the perfect cure for VNDA (V-Neck Depth Anxiety). (Just call it "vanda.") Thus:
"May I help you?"
"My doctor sent me here. I've got a bad case of vanda. He wrote this prescription."
"Ah, yes-a Z-neck. Right this way, please. By the way, our new line of casual shirts just came in."