I've missed my period this month, but I have tender breasts, bloating, cramps, headaches. It seems like I could get it at any minute...but not yet. My husband had a vasecomy about 3 years ago and after we were 100% sure he was sterile I stopped taking birth control pills. I've had very short periods (3-4 days, and very light) since then but they were very regular (every 24-28 days).
My husband thinks I should check with my gynocologist to see if I'm for sure not preganant, but I'm willing to wait and see what happens next month. Since I just turned 45 about 3 weeks ago, I'm pretty sure it's premenopause.
Could someone give me some insight?

It could be perimenopause starting up. Pregnancy is possible, but it would be very unlikely due to your age and your husband's vasectomy. This cycle might just have been off. I'd see what happens when your next period is due. If still no period at that time, then give your doctor a call. They might decide to do some hormone checks.