How long should i wait before going back to skydiving after a breast reduction?

You should be just fine skydiving 6 weeks after  a breast reduction if you didn't have any post-operative healing complications. 

Asking questions so you can find other opinions is self-serving in  my opinion as you are only looking for someone to back up your desires to resume activities sooner.  Why the resistance to following your surgeon's advice?  If you resume skydiving before 6 weeks, you are doing it at your own risk of some problem arises from it.  And if its topless skydiving, even longer because its amazing what distortion you get from the wind.

I would consider 6 weeks to be the minimum and would probably advise 8 weeks. This assumes that all the healing has gone well and the breasts are comfortable.Obviously you should be off any medication / painkillers that could affect your judgement before resuming skydiving. (It would be unusual to still be on medication at 6 weeks and if you were there would probably be other reasons for not skydiving i.e. not fully healed).Primarily you should follow the advice of the surgeon who carried out your surgery.

Your doctor is right and I would not do anything strenuous for six weeks if you want to be safe.  I would listen you what you body tells you.   If you are doing too much, you should back off your activities for a week or two.

I tell my patients that they can resume normal activities 6 weeks after a breast reduction- at that time the tissues have regained 70% of the final strength and are strong enough to withstand most forces.  But most patients tend to wait 6 months to get a mammogram because the breasts may still be a little tender.  A parachute popping open may be a lot of force and you may feel more comfortable waiting longer.  But the incisions should usually be strong enough by 6 weeks.