My lime "bushes" were very prolific growing in pots this year. And they are very large...perhaps 1 and a half to twice typical size. But when they matured and were ready for picking (falling off the bush), they were yellow like lemons. They taste good as limes and there is no question that they are limes. They got organic fertilizer and miracle grow over the year. Why are they yellow? Is it a lack of nutrients? Apparently, they are healthy because they have started to blossom again even as mature fruit is falling away from the plant.
If the limes are yellowing, they are over ripe. You should pick and harvest before they start to turn yellow.
Here are some links to help you.