Probably nothing. Can you post a photo? Sometimes immature Meyers will produce flowers lacking the typical purple base of the bloom; normally it is just a case of immaturity of the tree, as flowers without the purple base rarely set fruit. Have faith and patience.

I may be wrong about this, but I was told the flowers have to be pollinated in order to set fruit. I had a Meyer indoors that kept dropping blooms, and when I moved it outdoors, it started setting fruit. And indoors it was in a bright room with a huge east-facing window, and it thrived other than no fruit.

That was years ago- these days my Meyer (the same dwarf tree I got 8 or 9 years ago!) is in a very large pot (about 36" across and 30" tall) on a dolly in my yard. If it's going to freeze or frost I roll it into my garage until it warms back up. I got a sturdy furniture dolly from Tractor Supply for $15 and it is a lifesaver! This was in central Georgia; I recently moved to the Florida Panhandle and have no concrete on which to roll the dolly, so it's now living next to my well house, I drape a tarp over it and the well house when it's going to frost/freeze. So far the warmth from the well house, water tank, and heat lamp in the well house has kept it fine.

I get literally 100+ lemons per crop off this tree now, and the tree itself is maybe 3 feet tall by around 4 feet across. It often has mature fruit (HUGE lemons often as big as a baseball!), green growing fruit, blooms, and buds at the same time.

About every 3 years (it starts doing poorly when it needs it) I pull it out of its pot, shake all the soil out of its roots, repot in fresh citrus potting mix, and pray I didn't kill it! I do it when the tree has no fruit on it, because doing it while there are blooms or fruit causes it to drop the blooms and fruit.

I also only prune as needed to control unwanted growth. I just nip a branch or bud occasionally, never a lot at once.

I thin the lemons it sets. I wait till they are marble-sized, then remove any that are scarred or misshapen. Then I remove some if it has what I decide are too many in one spot, because leaving too many on the tree results in smaller fruit, and I like BIG lemons!

I fertilize pretty haphazardly- usually I toss a handful of 10-10-10 on it when I'm fertilizing something else. I have used "citrus fertilizer" as well.

Finally- I have accidentally left it out in the freezing cold, and the result was it dropped all the leaves the frost killed. It also dropped all the blooms it had and buds that were forming. However, I took better care of it the rest of the winter and in the spring everything grew back.

Meyers can be tricky to get the hang of, but are totally worth it!! I have fresh lemons 9 months out of the year most of the time, thanks to its habit of setting successive crops of fruit throughout the year if it's happy.