The international standard eye chart is 1.0-2.0. In fact, the standard eye chart is different in different countries.And different jobs have different limits on eyesight.
You say that you need -1.5 that is to say you are nearsighted. But it is hard to say wether you have a bad eyesight or not. You can go to see a eye doctor, and let him or her give you a complete check.
Well, bad eyesight may refer to higher than a -6.00(600 degree) of myopia. From the result of your optical test, containing some terms and abbreviations, some numbers on your eyeglass prescription mean different but specify your prescription. "OD" and "OS" mean the "right eye" and "left eye". Sphere (SPH, amount of lens power), cylinder(CYL, amount of lens power for astigmatism), axis( added magnifying power) and prism( amount of prismatic power), both of which help to correct nearsightedness or farsightedness. In general, sphere, add and cylinder power will appear in diopters. Your degree is normal. I have -3.00 prescription eyeglasses, and go to my optician regularly to see some possible increase of the degree. In addition, the sharpness of our vision will decline with the deepening diopter, extended axial length and some fundus' pathological deterioration. As we all know, eye fatigue has a lot of eye health hazards. The more time you sit in front of your computer or TV, the higher your degree.
Well, for your situation, I have to say that you have bad sight, for you are near- sighted, and also have - 1.50 prescription eyeglasses. And when you suffer bad sight, it is very necessary to have eye glasses with certain prescription. So that you can just see things clearly. But on the other hand, if you want to correct your sight permanently, you should consider taking eye surgery, such as lasik eye surgery, which is designed to correct vision for near-sighted and far-sighted people. For details, you can have a talking with your eye doctor.