Yes, drinking from a bottle is easier for a baby because it is just gravity. Versus drinking from a breast, requires a whole other technique for "sucking" and mouth/tongue coordination and the baby sucking to get the letdown going etc. So, some babies start to reject breast drinking.
My son was a bit like that... and by 12 months old, he weaned himself.... and he would literally SHOVE my boobs away and not want it... but would take a bottle. But, I kept nursing him until 1 year old... despite.... and he did so... but was grumpy about it at times. But... he did latch on for a LONG time... so I know he was getting to the hind-milk and nursing sufficiently. And I saw/heard him drinking... and swallowing.
For the 1st year of life, solids is NOT a baby's primary source of nutrition. Breastmilk and/or Formula is. "Solids" for the 1st year, is pretty much just an introduction to "food" and eating. If you increase her solids... then that will make her too "full" to nurse, or to take her bottles. You should ALWAYS nurse or give the bottle BEFORE solids. Otherwise, if you give the solids 1st, this makes the baby "wean" from breast/bottle.
This is also per our Pediatrician.
I know it frustrating because she rejects breast for the bottle because its easier. And even if she is at the breast, she barely stays latched on long enough to even get to the hind-milk. For a baby to reach the hind-milk... it takes about 15 minutes of sucking. Otherwise, they are not getting the full benefits of the breastmilk...
And pumping is not easy and often times not much gets pumped out. I was like that too.... even though I had a lot of milk in my breasts. It just didn't pump out a lot. I could tell my kids were getting a lot of breastmilk however... because I breastfed exclusively.. and they grew like weeds and their weight-gain and "height" growth was in the upper 95-98th percentiles, Consistently, and they were always satisfied after nursing. Except during growth-spurts, when they nurse more often and just more, 24/7.
Main thing is... that baby get enough intake... and not substituting breastmilk with solids.
She has to get adequate intake... and at this age... she most likely can drink more than just 4-5 oz. bottles of your milk. A baby that age... typically drinks more than just 4-5 ounces..... and more than just 3 bottles a day.
I know its hard... but if she just will NOT direct nurse from your breasts... she STILL has to get nourishment... via pumped milk. But if that is not adequate intake... then you need to supplement with Formula. Although lots of Moms abhor that. It is a personal decision.
She may also be rejecting your breasts... because there is not enough output. This is common as well... when pumping. It diminishes milk supply.
Perhaps, even if she just latches on for 5 minutes... have her latch on frequently once you get home.. to stimulate your breasts to produce more.
For me, at least my son went to 1 year old with breastfeeding... but by that time, he really just had it. He weaned himself. Then I segued him to whole milk... and toddler formula. Per our Pediatrician. Because he was a very picky eater and just would not eat solids many times. But still, despite, his weight gain/growth was good and healthy.
Try asking your Pediatrician, or a Lactation Consultant.
Every situation is different.
all the best,
Susan