Weight gain?

Brittany
So I see my doc on Thursday and of course will be asking but what is not acceptable for weight gain? Before finding out I was pregnant I was about 130lbs 5'5" not super skinny but not heavy either. Well during first trimester I got down to 124 at lowest. And now at 26.4w I am barely back at 130. I cannot seem to gain any weight though I fought to gain the 6lbs I lost back and cannot seem to break that 130 mark. When does it become worrisome? And are there things I can do? I eat a fairly healthy diet and have even added organic protein shakes to my diet as well. Just want to make sure my baby is going to be okay. Thank you 
Oh btw to my previous two pregnancies I gained normally never lost like this one.