Can’t gain weight 😫

I’ve even been diagnosed with hypothyroidism and haven’t started my meds yet (get them tomorrow) and still can’t gain. I was 5 lbs overweight going into this pregnancy but am 8 lbs below my start weight at 19 weeks. My doctor thinks I’m not eating but I am 😫 just nothing is sticking. Any tips without adding unhealthy fats and sugars? I had a temporary boost but it was from constipation and now that I’m pooing like normal it’s dropping right back off.

This is my weight since my January bfp