My DD just turned 14 months. We have been practicing 'gentle' and 'nice' touches for a long time, and she recently started to say, 'den-tull' and 'niiii' (she has a lot of words already.) While she says that, she softly pats us or herself. I told her to be gentle with the book, when she was throwing it and the pages were getting crinkled, and she started rubbing her own leg, haha! Any way, the last 2 days, she will be in the middle of petting/patting me or DH on the face, saying, 'niiii', then she will draw back and slap us! Sometimes she draws back like she's about to slap us, then still gently pats us. She seems to think it's quite hilarious, too

We hold her hands and say, 'gentle' sometimes, we've said 'ouch', and she seems to think both of those things are hilarious. I've put her down when she is hitting, but it feels harsh to me. Then again, I'm having a really difficult time laying any boundaries at all with her because she has rarely cried in her life...she's always very happy & the crying has always been like 15-30 seconds or less...but when I am giving her boundaries lately, like not holding her on my lap at the computer if she pounds the keyboard, or not letting her hit me, or not letting her dump all of the milk out of her cup, etc...she SCREAMS and continues to scream her most upset scream...it lasts for a minute or two, which is just so long for my happy baby!
Does anyone have any advice? I'm going to try the 'hands' song mentioned above, but I've tried the other things and she is definitely not getting it at this point...is it maybe an age thing?