J.S.
It's a fairly new thing that they recommend the vit D drops. I have a 2 year old who was exclusively breastfed. The dr. didn't make any mention of vitamin D then. But a had another baby last April and was told if I exclusively breastfeed I should give vit D drops. I bought the poly-vi-sol and tried to give them to her, but she hated it and would spit it out. It stained her shirt and smelled horrible, so I didn't give it to her anymore. I just thought if it had stuff in it to stain her shirt then maybe I should do more research. We just had our 4 month check-up last Monday. The doc asked if I had been giving the vitamins and I told him I had not. He said if she gets outside every day and gets indirect sunlight (even getting in and out of the car) she should be fine. He said it's pretty new research. So, I don't do the drops. I don't think you need to worry if you haven't been giving them.
Not to sound like a conspiracy nut or something, but I have noticed that now that breastfeeding has gotten so much more popular and there's all the "breast is best" messages around, the formula companies have started making these supplements. There are supplements for breastfeeding mothers to take and the poly-vi-sol both made by Enfamil. I was given these things as "free gifts" along with lots of formula at the hospital and at my drs office. So, I really think it's more of a marketing thing -- trying to break into the breastfeeding market since breastfeeding can be done without purchasing a single thing.