Mild neck swellng, diagnosed Goitr B/L 2-3 fw mm colloidal cystc swelling, on USG, otherwise all blood test within normal limits, & no S/S. non surgical T/ T?

Depends. You need your iodine, tsh, t3, (liothyronine) T4 and parathyhroid levels checked. You also need a special thyroid scan if not already done. Lastly, a biopsy may be indicated. The answer as to what tx depends on what the cyst really is. Sometimes watchful waiting is enough but if it appears "strange" removing it makes everyone feel better. You can send your image to ucsf for a second opinion.
See your doctor. This is a problem that requires a face-to-face meeting with your doctor. In that meeting, your doctor will listen to you, perform a throrough examination and possibly order labs or other tests. Based on this information, he/she will be able to tell you what's wrong and what to do about it.
Thyroid cyst. At this size of the cyst, would recommend thyroid sonogram every 6 months to monitor; check with endocrinologist and general surgeon also.