it does usually take a bit for a little one to get used to the routine but i would try to tough it out, even if it means letting her cry for a little while(i know i cant do it, but i started the routine from day 1) i read an artical just the other day about a couple trtying to break their 3 month old from sleeping in bed with them- every so often they would come spend a few minutes with her to calm her and reassure her that they were still there, but then leave again and eventually baby would wear herself out... it took like 5 days for them to get much REAL sleep, but eventually, it came out okay...
and being at your moms every weekend CAN be part of it, however, if you continue the same routine there, it should even out eventually...
and the lavander scent- it doesnt exactly enduce sleep, but its a calming scent and it should help to relax Emma