I've heard anecdotal evidence that after being on hormones for a time, at a constant dose, your body will start cycling naturally. 

I've noticed this in myself, I go through times where I run hotter than normal. But most fascinating is I seem to be syncing up with my girlfriend. When she gets her period I find that my vagina gets really 'juicy', to the point where I develop a rash and I need to change my liners every 3 or 4 hours or so.

I don't seem to have any mood changes, but it is hard to tell since I have a mood disorder anyway.

Have any of you experienced a natural cycle? That is aside from those who are intersexed.

  I'm pre-op so I can't speak for those that are post-op, but I don't think so. The hormones we take are synthetic and we don't have ovaries like cisgender women so there isn't any natural cycling involved.

But there are other things in you that produce and regulate hormones, like your adrenal glands.

I have a few friends who have noticed a cycle too. One of my friends gets incredibly grumpy and short tempered around the time her misses has her period. I have read others say similar things before. It seems like a real phenomena.

I do shots so that right there is good for ups and downs over 2 weeks to 10 days

Since we barely have an understanding of pheromones in general, much less on humans,  I give it a plausible that you can be affected by your g/f's cycle. There can also be a psychological factor involved too. Either way, I think it is cool that you are.

Even males have natural hormone cycles, so I don't think it's impossible. Though it does appear unlikely. It's not like your body produces or stores the hormone; you yourself administer it at a fixed dose. Though it might be something else that is cycling. For example, the small amounts of E, T and P that your adrenal glands make. Or FSH/LH. Or thyroidian hormones. Or anything. But whatever it is, I doubt it's linked to HRt itself. Actually, if it does happen, it's probably something that has happened all your life. Maybe before it was just masked by the heavily distorting effects T has on character. You couldn't feel more excited, since T is like freaking Viagra 24/7. You couldn't feel more upset, since T made you feel pissed most of the time anyway. Or something like that.

There may be a psychological factor: your brain tells your body it should be cycling, so it looks like it's cycling. Or you might be just more attracted to your girlfriend when she has her period. Pheromones or something.

So true hun, I like her bloody 

I do seem to have at least a emotional cycle of about 28 days? At the university other students jokes that I was PMSing because one week every month I was in a bad mood.

I never had my hormone levels checked during a month so I don't really know.
Maybe someday when the equivalent value of 500 euros in 2012 isn't a lot of money any more for me...