For the 1st year of life... breastmilk or Formula is a baby's PRIMARY source of nutrition.
Solids... is NOT as nutritionally dense... as breastmilk or solids.
And you should nurse on demand. Still.
Not replacing nursing with solids.
Solids is, again, not as nutritionally dense, as breastmilk.
I nursed my kids, and did not give them the Polyvisol w/iron.
They grew like weeds and were very healthy.
You REALLY should be talking to your Pediatrician about this.
We are not Doctors.
Then, babies do get distracted when nursing. So, when you are nursing do NOT do it, where your In-Laws are. That is counterproductive.
Go to a room to nurse, where it is just you and your baby, and where it is quiet.
And make sure your breastmilk supply is adequate.
Because, she has poor weight gain.
And at that age, a baby does NOT have to "eat" 3 meals of solids a day.
Breastmilk or Formula, should be the priority.
AND, ALWAYS... nurse BEFORE giving any solids. Otherwise, baby will be too full to nurse, after solids.
That is what our Pediatrician, said.
As a baby gets older, they do not always nurse on the dot. They do not nurse according to a 'schedule.' They need to nurse, on demand.
Before any solids is given.
My kids were on solids by that age, but they nursed, a lot still. And often. 24/7 day and night. And especially during growth spurts.
For the 1st year old life.... "solids" is ONLY an INTRODUCTION, to "eating." It is NOT a baby's primary meal.