Weight Gain

So I'm feeling a little overwhelmed with being 9 weeks 6 days and feeling like I've gained so much already. 
I seem to be either 145 or as high as 153 (or somewhere in between) fluctuating daily... I'm 5'7 and always been on the thinner side (125 to 135)  but honestly have no idea what my pre-pregnancy weight was to since I have a tendency to worry about gaining weight and wasn't keeping a scale in the house until we confirmed the pregnancy. 
I really dunno what I'm trying to achieve with this post, but do any of you other mommies to be seem to be putting on weight and fluctuating like this?