Good day!

I am doing my research study.
My dependent variable is Corruption Perception Index.
My Independent Variables are:
a. gdp per capita
b. life expectancy
c. infant mortality
d. tuberculosis incidence
e. undernourishment rate
f. persistence to primary education
g. births attended by skilled health personnel

My study seeks to formulate alternative formula for Quality of Life, actually. The a-g independent variables are the indices of Quality of Life base on my literature.

First, I have used the Panel Regression (OLS, FE, RE), I got the result but there are some issues with insignificance of the variables specifically in the fixed effect model.
Do you think that OLS/FE/RE will be enough and appropriate to my study?
And so, I decided to use the SURE (Seemingly Unrelated Regression Equation) to formulate different equation per independent variable.

SURE vs OLS/FE/RE

What post-estimation can I do in SURE?

What do you think guys? Am I doing the right decision here?