1) If you were told it was 140, it's lower, 140-, as in not higher than 140.
2) People with an IQ of 140- have a lot in commmon with people who are of average intelligence. Most teachers are of above average intelligence.
3) You will have more trouble adapting to highly intelligent people than to average or above average ones. You have less in commmon with your professors than you apparently think and they will have to adapt to you, so you understand them.
Good luck, 140- is not what you think it is. Work hard, try not to lose your positivity, which you unfortunately currently tie into your belief that you are the smartest guy in your future. You won't be. Even the 160 IQ people, one in 10,000 (no, not the much larger group told they were 160, the real 1/10,000 people), have daily challenges in a competitive environment, or an occupation where other smart people cluster. Effort is the more important characteristic, even for them.
If you want to be a teacher, you, as anyone will have challenges, but you being too smart will not be one of them. Intelligence is a resource, not a handicap. Your notion of a person being "overwhelmingly smart," is kind of fanciful. It might apply to someone, but not to the millions of people who are 140-. The 1/10,000 160 IQ people mostly blend in very well in any envionment, but the odd ones don't. Same is true for 140 IQ people. They mix in easily, except for the odd ones. Honestly, thinking 140 is "overwhelmingly smart" is what people who nearly fail high school might think, not what most really bright people think.