First trimester, worst trimester?

Shelley
With my youngest being 15 I realize there is a lot I have forgotten about pregnancy and my 38 year old body isn't going to handle the pregnancy the same way it did when I was just 23. 
Tell me, which if the trimesters was the worst.   
I know that being just over 9 weeks I have a very long way to go, but the pregnancy brain, exhaustion and the side effects of the hormones...  I'm just tired.  And cranky.  And dumb.  Lol.