Toddler Weight Loss

We are concerned about the weight loss Sasha has experienced over the last three months. At her 12 month exam, she weighed 18lbs 14ounces, and at her 15 month exam, she weighed 18lbs 8oz; so she has lost 6 ounces. I suppose that might not be much, but it's a weight loss when she should be gaining. She used to be at the 50th percentile for weight for her first 9 months, but now she's dropped below the third percentile for her weight at her age.
I know that toddler growth slows down after a year of age, thus requiring less food. But Sasha was always a picky eater. Actually, she just didn't seem to like the eating concept in general. But within the last few weeks or so, Sasha has finally started eating.
I wasn't surprised that her gain wasn't as large as most children should be. But even before her well baby exam, I knew that we would not see much of a weight gain. The loss of weight was a surprise to me, however.
My hope right now is that because Sasha is actually increasing her food intake by leaps and bounds lately, that her growth rate is now increasing. I don't know if it's enough to make up for what she hasn't gained before, but she is definitely improving. Of course, the doctor didn't seem to understand that she was already on the increase.

For now, I think our plan is to continue to offer her foods many times a day. Instead of three meals a day, we do a bunch of mini-meals and try to keep her constantly grazing.
Despite the doctor suggesting we wean Sasha, I really don't want to do that during the middle of the cold and flu season. She gets extra immunological benefits from nursing. Several times I have seen her fight off colds and flus that have laid my husband out and I attribute that to the benefits of nursing. I am encountering a lot of sick coworkers, and I am afraid that I am bringing some extra germs home to my family. So I do not want to wean her now. Instead, I am trying a new tactic. I do not nurse Sasha until after she has eaten all she can at a meal. Then I top her off with a nursing session. She always has room for milk and regardless of how full she is, she never ever refuses nursing. It's like her dessert, lol.

I do want to keep trying to give her nutritional foods, but I do admit it has sort of become a feed-Sasha free-for-all, where we give her anything that interests her. Sweets, high fat foods, anything that she'll eat. Bad foods are better than no food at all, right? I am hoping that we can curb this after we get her weight problem under control so we don't develop some bad eating habits.

Articles I am reading on how to feed picky toddlers:
Dr Sears- FEEDING TODDLERS: 17 TIPS FOR PLEASING THE PICKY EATER
Dr Sears- IS YOUR CHILD GETTING ENOUGH TO EAT? HOW TO TELL
kellymom- Nutrition for nursing toddlers
Boosting Calories in your Child's Diet

Toddlers like mine and their mother's takes on the problem:
Mothering your nursing toddler
Berkeley Parents Network- Toddlers Not Eating