dont be worrying you are only 13 and have raging hormones its way to early to label yourself as anything. wat you are doing can be seen as experimenting, many str8 guys do that and they are not gay. its just about growing up.
and even if you were gay its not the end of the world. your dad makes it sound so bad, its not.
as for wat should you do, do wat ever makes you happy. dont worry about am i gay? is this wrong? enjoy yourself and do wat you want ignore wat anyone else says.