For the title question “Is it possible for me to get a 3.8 or higher unweighted GPA?”, you can calculate your maximum possible GPA (presuming you mean end of 11th grade for college applications) by adding to your current record a hypothetical record of all A grades for the courses you will take until the end of 11th grade and then calculating GPA based on that.
Of course, the harder part may be to become a better student to actually earn all A grades for your remaining courses in high school.