Confused

So I'm not sure where to start. I've just missed a second period, done the pregnancy tests, they've come up negative, done the ovulation tests, they've also come up negative, every single one. I'm putting on a little weight round my belly, I'm not eating anymore food, in fact I've eaten a little less food. I'm always tired, I'm snappy and moody, tired again. Obviously I'm not pregnant as I've not got any symptoms apart from the missed period. Just wondering if anyone has an idea of what it sounds like? I don't think it's stress, I had that last year and it only made my periods a little less regular. I'm 33, TTC and I'm hoping it's not early menopause. Oh and I'm kind of going to the loo a little more, and I have way more gas than usual, I've never burped so much than I have these last few weeks!