Similar experiences???

I'm 20 weeks today, and I feel like so many things changed this week.  I tend bar, so am on my feet for 5-8 hours straight. This is the first week I really felt it.  I was completely exhausted by the end of each shift.  I also told my boss, I need to significantly decrease my hours.  I have ankle, and foot swelling for the first time, and although I haven't gained a lot of weight this week, my belly is out there now. The actual shape of my body changed drastically. This all just seems odd to me.  I didn't know it happened that fast.  Is this normal? One week I feel like my regular self, and now this week I feel... PREGNANT!!!