Experience needed please ladies

Chocodoxies

Ladies, I need some advice. Let me know what i could do, should do in this situation please? I am sorry this is so long.

My DD is now 3 weeks old. She was born at 7lbs 1oz, and left the hospital weighing in at 6lbs 5oz. No use of formula or binkies, and nursing on demand. She has an excellent latch. With my first DD I did not know that I had Hashimoto's Thyroiditis, and thus my milk came in, but never met demand and by three months old my milk supply and diminished despite tinctures/pills/teas/etc. to nearly nothing. Now my hashimoto's is under control.

Three days old, I took DD2  to the NP at her pedi office and she asked me to give one ounce of formula a day to her to help until my milk was in fully, I was also given a nipple guard. My milk came in that weekend, my nipples are fine, so both formula and the nipple guard are no longer used. Since then her weight has increased to 6lbs 14oz and she is a champ eater. Today we took her in for her final weight check and she has lost a .5oz in a week.  I am so confused!  

She is satisfied after eating, and sleeps well. She wets 6-8 diapers a day, she poops 3-5 times a day, and eats every 2 hours or so for 20min per breast. She sleeps an average of 3-4 hours at night and she is not a cryer but a very content baby. I am taking fenugreek, 9 pills a day, and have upped my calorie intake. The only thing I think could be affecting her weight was the flu that I had this week (she did not get it thankfully). I couldn't eat much so my caloric intake was low, however even vomiting I was drinking plenty of fluids.  

I am desperate to keep EBF. I had that experience stolen from me and DD1 and I love it so much, I don't want to have it stolen again. Can any of you ladies suggest anything?