I too am curious. Men don't have hysterectomies, so I shall assume you mean vasectomy? If so, then yes, it can happen. Not common, but it does happen. The thing is, if you took a pregnancy test at day 33 and it was negative, it's probably unlikely. There are so many reasons we can have trouble with our cycles...everything from stress to another medical condition. It does not necessarily mean menopause, although in a few women it can come early. I would suggest a visit to your Dr. Good luck.
Are you talking about your husband having a vasectomy? Or you having a hysterectomy? I agree, if you had a hysterectomy, there is no chance of pregnancy. If your husband had a vasectomy, the chances of the tubes reconnecting are less than 1% but not impossible.
I'm not a doctor so all of this is just what I know from the women in my family and some of my friends. A hystorectomy would make it impossible for you to be pregnant because they take your uterus and your ovaries out. Even a partial hystorectomy would make it impossible because even though they leave your ovaries, your uterus is still gone. If you meant that you had a tubal ligation, then you could still end up pregnant, but the chances are slim. Once you get into your 40's you can start experiencing some irregularity as you may go into perimenopause up to 10 years before actually menopause sets in.