I repotted a couple of citrus last summer, Page and Clementine. At that time when i repotted, they already got fruit on them.

But so far this year, it's almost May, they havent even bloom/flower yet, but the leaves look pretty healthy. I fertilized them a couple of times so far this spring already, still nothing...

How did they spent the winterperiod? My citrus suffered from the cold weather and are now just starting to 'regain power' i.e. producing flowers and leaves and still this is a very slow process. I guess the root system needs to recover fully.

Might be similar depending on how your citrus spend their dormancy.

Besides that I did hear once that some citrus can produce nicely one year and do not produce a single fruit the next year.

actually had a pretty mild and warm winter....

If they have not flowered by now they probably wont this year. They may be recovering from stress of some kind. I have trees that have done that before after a heavy load the previous year. Pictures may help understand your problem if there is one...