I'm not totally sure, they say it is safe, and I took it with my DD until she was 6mths old, and she seems fine now, at 4!! We were still combination feeding with some formula, but mostly BM, but if I went off the motilium, my supply dropped really dramatically, no matter how slowly I tried to do it, or how much I tried to increase my supply in other ways. But, for me, I wasn't terribly comfortable with having to take drugs to have enough milk to still only partially feed my baby. It didn't seem to be helping me for the longer term since I couldn't wean myself off it and still have a decent enough supply (itms!). So I decided to stop taking it when she was on solids properly as in 3 meals a day (about 6 1/2 mths as she started solids at about 5 1/2mths). I still offered her booby, though she was mostly formula fed afterwards, and as it happened, I ended up pg again when she was 7mths old and she wouldn't have a bar of boobies after that anyway!
Good luck with your decision. I know how tough it is.