It is difficult to say exactly what will happen to your milk supply if you reduce pumping to twice a day. Some mothers would be able to resume feeding their baby with no problems and others would find that they have to work at increasing their supply.
This wouldn?t be the case with a much younger baby but as you have already been breastfeeding for six months it will take your body a while to decrease the supply. (The younger the baby the easier it is to loose your milk.)
It is important to remember never to leave your breasts uncomfortably full. Being full is the biggest signal to your body to stop making milk. You may find that expressing twice a day isn?t enough to avoid the full feeling. If this is the case then try to pump more often.
Remember if your bladder was full you wouldn?t think twice about emptying it so have the same view with your breasts. When they are feeling full empty them.
If you want to wean completely just take off enough to be comfortable again. If you want to continue breastfeeding take as much milk as it is possible to get in a reasonable time. Usually you get more milk to express in groups of five minutes. (e.g. five minutes on the right breast, five minutes on the left, then another five on the right and another five on the left.)
One study showed that it took an average of 42 days (six weeks) for a mother to stop producing milk after her baby weaned.
If your milk supply is low when you return home, remember that a couple of days feeding the baby as much as possible will increase the supply again. Try breast compression,
http://www.breastfeedingonline.com/15.html. Also try switching breasts (the mothers I?ve helped have found switching breasts to be very efficient.) Feed on one side until the baby stops, then the other side, then return to the first breast again. It is fine to switch 6, 7 8 or even 9 times in one feed.
Best wishes,
SARAH