Is your car fitted with the R4 compressor ?
If yes, it has no sump... so the oil needs to be split around the system if possible. Probably too late for that now... probably better to add it at the 134 valve now which will accomplish that somewhat...
Did you flush in sections as you had them apart to renew the o-rings ?
If you have the R4 compressor... Did you use the old manifold ? The AC manual says to put a new one one as it can not be cleaned ... this means that if the reason your compressor went bad was lack of cleanliness by the former owner or AC work you may be putting your new compressor at risk.