I go through phases of 'I'm okay' and 'omg I'm hideous', too. One thing I've come to realize that others perception of me (which I have no reason to doubt) is fairly different from my perception of myself. E.g., I think of myself as having a 'chunky' build whereas others describe me as 'slim'.

One thing that has really helped me... Is joining the gym. I don't care too much what I look like anymore, instead my focus has shifted to what this body can do. What this body can do can improve with some hard work. What this body looks like... Well... So long as I look healthy I guess I don't much care anymore.