Newbie here, so please be gentle... 
I'm 40 and trying for my first baby. For the past three years my cycles have always been 27-28 days, with a 5 day, fairly steady-flow period but for the last couple of months my body has gone completely whacko. Last month's cycle was 34 days. I took a pregnancy test on CD33 that month but it was negative. Anyway, then followed a really short (3 day) period - light first day, very heavy second day, very light on third (sorry if TMI!). I'm on CD34 again today and no period.
I've got some weird stuff going on in my body that I've never noticed before with my periods - dizziness, and some nausea on and off at different times of day for the past couple of weeks, plus this week I've had weird...not cramps but something going on downstairs, and sore boobs... In addition to that, I'm suddenly waking up in the night to pee so actually there's not been a time where I've gone more than five hours without peeing for me to test (again, sorry if TMI!). That said, I've tested first thing in the morning on CD30 and today and negative both times.
So, I know I can't actually be pregnant and that I'm probably noticing this stuff because I'm more 'in tune' to my body but I guess my question is, is this 'normal' PMS stuff (for two weeks!) that I've never had/noticed before, or am I possibly looking at menopause/peri-menopause here?
Thanks in advance for any help you can give me 