Be aware that this is the English spelling of a Korean word. The written syllables are approximations of the way that Koreans say the word. Some people also spell “umma” as “eomma. "
Try watching Korean movies and shows to get an idea for the cadence of the language. There is no guarantee that you will hear a lot of the word “mother,” but you may find that it’s easier for you to naturally say the word if you understand the context.