I am analyzing satisfactions level of Phd Scholar in a particular region, We got 7 Independent Variables from literature review and constructed 45 questionnaires accordingly , for example we 5 questionnaires related to stress, 4 questionnaires on scholar-guide relation etc ,

I have done reliability test of all the 45 items (combining all the items of 7 independent variable), we found Cronbach alpha 0.750 which is reliable but when i try to do reliability test for questionnaires related to only stress(only one independent variable) it is showing 0.44, similar for another independent variable showing below 0.7. Is it reliability test reliability necessary here as i have pick all the independent variable from Literature reviews but construct my questionnaires related it as it was not found in the LR

I have done step wise regression on the Mean(calculated compute variable) of 7 Independent variable and found this enter image description here

I am really confuse if my analysis is going in right direction , Please help

Model R R Square Adjusted R Square

1 .544a .295 .291

2 .584b .341 .334

3 .608c .369 .358

All the model is significant