What signs indicate an 11 month old is getting enough breastmilk if they also eat a lot of solids?

Wet & Happy. The short term answer is that if they are wetting their diaper 6-10 times a day, their mouth is moist, they are not having hard stools, then they are getting adequate day to day fluid intake. The long term answer is that if your child is gaining weight according to his or her growth curve, then they are getting enough. Remember, milk intake amount needed decreases alot around the first birthday.
It's a supplement. For an 11 month old who is eating solid foods, breastmilk is a supplement and is not really a requirement. You may choose to continue to breast feed for a variety of reasons, but your child has already received the health benefits from breast feeding.
Baby acts not hungry. A healthy, normal-weight baby is getting enough breastmilk if she breastfeeds a little while and then smiles and starts goofing around. Be sure she has a variety of solid foods if solid foods are a big part of the diet (she will be missing some nutrients if she only eats one or two types of solid foods). At the 1-year old check-up, the doctor can check her growth and do a blood test for anemia.