Your description matches with my tag.
http://www.mangago.me/people/tag/2337/Seme-looks+Uke/
i love those types of pairing, lol. especially check out those that i marked as "dupe roles" so here's the seme that you wanted. http://www.mangago.me/home/mangalist/22922/
Have you tried "Nirameba Koi"? I highly recommend that if you haven't yet. Apart from that, you can try Mishima Kazuhiko's works. Almost all her works have a twist like that.
http://www.mangago.me/read-manga/nirameba_koi/
http://www.mangago.me/r/l_search/?name=mishima%20kazuhiko
Yaoi or shounen-ai with unexpected Seme? Like, when you see person A, you think he'd be the Seme but turns out, person B is the seme. Not shotacon,please. It's just not my cup of tea.
Thank you