for what its worth, heres my relatively newbie opinion:
- was the hairline lowered lower than the existing hair? from what i've seen, when you do this it often looks sparser. it looks like yours was
- the hairline itself, in my view, actually looks like a pretty good design
- i think what doesn't look good is the sparseness, which it sounds like a 2nd HT would help that. also, you've got different hair styles that make it look better. shaving it at different lengths etc. maybe a close shave would actually look the best at this point? that or growing it out more medium-lengh potentially?
- another thing to consider is that gray hair is way better at looking more natural and thicker. so when you get older and start going gray, it will look way better. although that could take awhile, so i'd understand wanting to get a 2nd HT in the meantime for sure. i wouldn't go any lower with the hairline, just density.