“Sometimes I get the feeling my superiors and co-workers think I’m inferior because of my accent”.
Some of the clients I have worked with in my accent reduction consulting business have wondered whether they were overlooked for job promotion due to their accent. In most cases, however, I don’t think it was the accent but rather the mispronunciation of the sounds of English which made it difficult for the listener to understand them.
There’s nothing wrong or inferior with having an accent. The problem is if you are not understood.
One of the ongoing exercises I recommend, to my accent reduction clients at EnglishWithoutAccent.com is to listen to a variety of audiobooks read by native English speakers. When you find an American accent that is appealing then you can practice imitating that accent. You might also benefit from a complete phonological analysis so that your pronunciation can be compared with that of the general American accent. Then your accent reduction consultant can develop a customized program allowing you to focus on correcting those particular sounds.