That guy is crazy, that’s a normal and healthy metabolic rate! Why did he make you worried! I got mine measured at the gym and it was something along the line of 1100 Kcal, which didn’t surprise anyone the slightest bit. I am 159 cm and was 49 kg at the time. I wasn’t muscular having never exercised, so my metabolic rate was low compared to my muscular and heavier husband, but completely normal for my body. If you increase your muscular weight (eat enough protein and do some strength exercises, which I personally hate 😄 So, I do yoga, which also helps to strengthen core muscles!) - I bet your metabolic rate will get higher.