1430 on practice test 11 and 1300 on oneprep??

This is my second and absolute last attempt on the sat because my parents will not be paying a third time so I absolutely need atleast a1450+ but it just so happens whenever I improve one section the other other shrinks?? And is one prep just way harder than the actual yeah or is it equivalent to the difficulty of the actual test? Because they say their tests are calibrated to match difficulty of the actual sat but I’ve heard many say it’s harder and bluebook is easier so what can even be an accurate estimate