why is the actual sat always harder than the practice

ive done every practice test and I havent gotten more than 1450 and im pretty sure im gonna get a 1450 from today. the college im trying to apply to is test optional but the average sat scores range from 1480-1550. I dont even think I can improve at this point and im tired of taking this test over again. this is my 4th time. ive even gotten an 800 math on the practice before but never on the actual test. can I even improve at this poinr?