It does sound like peri-menopuase espc. w/ the heavy & longer periods. I went through this in my late 30's and it made me crazy when I would get such heavy periods. I did not get hot flashes though until I got closer to full menopause around 43. I also have Hashimotos Thyroid disease and that makes me cold instead of hot. So yep thyroid can mess with your internal temperture gauge, so get it checked!!!
When you get your hot flashes do they start in your chest area and move up to your head and your feel like your upper torso has a heat lamp blazing on it? After my hysterectomy I get them randomly throughout the day, the best advice I have gotten is to dress in layers (since I live in Colorado too!) I have had to strip down to a mini layer of clothing to get relief in a store. It also helps to use your shirts as a fan, grab the collor and fan away. If people stare I tell them that I am "low on estrogen and own a gun..." Just kidding but I would like to tell them that when they look at me like I am nuts for fanning myself when it is 15' degrees outside :-)
I hope you can get to the bottom of this. I would have a whole bloodwork run up of Thyroid & hormone levels...