pain medication and pregnancy

[M.E.72]

. I have had severe back and neck pain for 7 years. After dozens of alternative treatments the only one that helped was medication. I have been taking Methadone 60mg/day(and sometimes more) for several years. My husband and I wanted to have a child, so I started weening myself. I had gotten to 2 or 3 10mg doses/day, with plans to keep going down. The pain is managable some days but very severe some. I stopped my BCP to be ready when I was off the meds to start trying and surprise the pregnacy came early. I do feel withdrawl symptoms when I try only taking 10mg or try skipping. My question is this: How bad is it for my unborn child when I go through withddrawls. Is it better to stay on a low dose, what can I expect for him when he is born if I stay on 10mg/day. I still suffer w/ chronic back pain and fear it will continue to increase as I get bigger. My doctor recommended to stop before I got pregnant, which was the plan. The withdrawls are very difficult to go through while trying to work and deal w/ pain at the same time. Any Advice??