Many of the symptoms of pregnancy but not pregnant

Hello,

Since early August I've had a multitude of symptoms that all resemble pregnancy (enlarged nipples, sore breasts, slight weight gain, food cravings, nausea, cramping, lower back pain, constipation, fatigue and mood swings). In addition to those my periods have been coming on time (relatively) but have been MUCH lighter than normal. I've been menstruating for almost 7 years and my periods were like clockwork since the start (even before birth control. They were also very heavy (even on birth control). This may be graphic, but to get the point across: on my heaviest day I usually go through 4 super pads and 3 super tampons. My first lighter period I needed only two pads and one tampon and this last period I used two pads but barely even absorbed anything on the second one.

I have been on hormonal birth control since I was 16, so I'm pretty sure these symptoms aren't just deciding to pop up now. All of my weight gain in in the very front in my lower abdomen. I try to eat right and exercise and it isn't going anywhere. I was freaking out so I took 3 home pregnancy tests. All came out negative.

I'm worried it might be something with either my thyroid or my reproductive system. I have a doctor's appointment in a week and a half (the earliest they could schedule me). But I figured I'd ask and see if anyone else had any ideas? Any comfort? I really am not freaking out about this too much and I'm not even that stressed. In fact I try to put it out of my mind until I have to find pants that fit...

Thanks for reading all of this. I really appreciate it!