Any group of guys will have incidences of the "morning tent" syndrome at almost any time of day. It has nothing to do with sexual orientation. It's a puberty thing.
Of course, that doesn't mean it can't be embarassing. If the 14 in your id relates to age, most of your peers will be having similar experiences. The best advice I can offer, difficult though it may seem, is to grin and bear it. In a few years, it will become less evident.
Also, I caution you about applying a 'bisexual' label to yourself. Many teens experience same sex attraction. It also is a puberty thing and does not define your personality.
I've agonized over this myself. So I have a pretty good idea what it's like. I expect you will be fine.