I've been killed several times by a wolf, and by a spider, and by a diseased deer, and even by a fish. You learn not to go strolling through the country like Little Blue Riding Hood (no, not a typo). If you think that's bad, just wait until you think you're being attacked by a little rat and it turns out to be an adult pit rat; 3 bits and you're history! Seriously, the area "levels'" are just a general guide, don't obsess over them.
Much depends on your equipment, weapons, skills, and most importantly, on your style of play. For example, I rely heavily on archery and "sneak" to kill enemies at a distance. Often, I can kill a strong enemy with one arrow, but if it gets close enough to hit me, I'm in trouble, and it might kill me in a couple of hits. With my style of play, I can play in areas quite a bit higher than my own level, with care. However, if you like to play hack & slash, and charge at everything with a two-handed sword, you have to get close enough so they can hit you, too, and in such a case, you probably need to be closer to the stated level. It also depends on your aversion to getting killed. Some players hate getting killed, and will wait until their level is so high they can waltz through a dungeon and take nary a scratch. I save often (hard saves as well as quick saves) because I enjoy the challenge of going somewhere that is "too high" for my level, and figuring out how to succeed anyhow; that's what is fun for me but it may not be what's fun for you. If I get killed, I reload and I know what not to do next time.
I suggest being a bit daring, save, and go somewhere like the Steel Rail Mine. If you have trouble, try changing tactics. If you still have trouble, wait until you are a bit higher level and try again. (By the way, I was level 9 or 10 when I went there, and by the time I finished, I emerged 2 levels higher!) Also, you will earn experience much faster in the higher-level areas because killing higher-level enemies earns more exp. points.