While concentrating on third eye, the first feeling i got was my inside was filled with bright golden-white light. But after some time as I progressed instead of feeling good, my deep seated fears surfaced and I started getting visions related to that. Why so? Am i progressing correctly?
Visual images sometimes come in meditation. If we are deep in meditative stillness and bliss, we may see images connected with the spiritual eye or with saints. These come because we have entered into higher consciousness, which is the goal of our meditation practice.
Other images that might come may be associated with day-dreaming, remembering past experiences, or negative emotions such as fear or worry. These images come from lower consciousness. If you experience these, consider them reminders to refocus your meditation on higher awareness. The bright golden-white light you saw when concentrating at the third eye — the point between the eyebrows and associated with a ‘good’ feeling — sounds like you started to touch into an aspect of the spiritual eye a bit. You might like to learn more about the spiritual eye and what it looks like when seen completely. If so please check out The Complete Guide to the Spiritual Eye.
If we do not use a meditation technique during our practice, our mind can become passive, slip into subconsciousness, and may be open to negative experiences. That sounds like your description of deep-seated fears. In your early meditation experience it seems you have been blessed to experience the contrast between the bliss of higher consciousness and the confusion and negative emotions that are found when our concentration weakens. To avoid the pitfalls of passivity in meditation I encourage you to learn a meditation technique which helps train concentration. Paramhansa Yogananda, whose teachings we follow at Ananda, brought a simple but effective and deep meditation technique called Hong Sau. You can learn it free here: Hong Sau Meditation Mini Course.
I encourage you to continue your meditative efforts that your life be filled more and more with the bliss of Divine Presence — not only during your meditations but throughout your days.