A good education is needed for a good start. Other wise, you 'grow from the ranks'. In working world, the work comes first and then comes education. Generally people compare in times of promotion etc. or at times of selecting which one to take ahead. Education enhances your mental capacity. Lectures and face to face instructions, interaction in class, discussing with others, learning others' view point is important part of the education. This advantage is lost in a distance leaning project.

Thus, you should aim at a minimum graduation course. Do it from any evening college, it will be better. On completion of graduation, look for PG diploma course in your own field of work. Keep this as your aim. Not beyond. This will give you all the confidence that is needed by you. Education is like preparing for a journey. While you may like to take all the bedding, all the clothes, every thing that you possess with you, but that is not practical. So you limit the luggage to the bare minimum. Here too, since you are already in job, spend only little extra time and not too much on education. Getting degrees will not earn you promotions, while commitment, hard work, will.

Your counsel.