Hard time gaining weight?

Cora • Mom of three💖💖💙 | Licensed Hairdresser🖤

I'm 18w1d and I weighed 129 at my last appointment. Like TWO weeks ago. I just weighed myself and I only weighed 130...I'm in the second trimester. I'm supposed to be gaining weight. Why is it so hard for me to gain weight? Is my metabolism working well like usual or should I start being concerned because I can't gain weight? A lot of the weight I do gain just goes into my tummy. :/