we used this nap time routine:
diaper change, swaddle, close the blinds, turn on the sounds machine (rain or white noise), sit in the rocker for 10mins, then shh-pat on my shoulder and into the crib. Continue w/ shh/pat in the crib until she started to settle on her own.
Until your LO learns to fall asleep independently and w/o the props she will fight you/sleep. But if you are consistent for all sleep then she will understand that sleep comes after the events above. Has your LO ever gone to sleep independently? Until a baby is old enough they don't have the skills to self-soothe, Shush/pat will teach independent sleep and is an excellent replacement for props like the breast. consistency is the key, w/o it your LO will be confused and won't understand what you want from her.
Are you using the 4S wind-down routine and making sure you're getting your LO into bed in plenty of time so she's not over-tired? I would also be aware of her A times, if she is overtired then this will also cause her to fight sleep. If you want to post your routine, maybe we can help.
What do you do at the one nap you do get?
HTH!