Some red leaves are normal for azalea but more red leaves could indicate a problem.
Azaleas like acid soil so first to check is pH of soil and water.
Also where in the world are you? I think it is too early in spring for azalea flowers in the northern hemisphere and way too late down here in the south where it is now autumn. Azaleas also flower on tips of new shoots so pruning will have a big influence on flowering if you trim the azalea too late the year before. If you want flowers in spring you must stop trimming at the end of summer.
There are many factors influencing how a potted plant grows and you have given almost no information.
Where do you keep this plant? inside or outside?
How often do you feed the plant? What fertilizer do you use? how often?
What size pot?
What soil is it planted in?
A photo that shows the entire plant might help give some more clues.
Unfortunately azalea is not the easiest species to keep as bonsai. If conditions are suitable they can grow very well but if they do not like something they will not grow and often just die suddenly.