Oh hun don't worry what the MCHN's or anyone says..... even the books can be waaaaaay off in terms of what babies should be doing. EVERY baby is different.
She will roll etc all in good time.... she's just focusing on her communication skills by the sounds of it loves smiling, chatting and giggling away.... my 5mth old baby girl is the same! She isn't very mobile yet.... she likes tummy time but not for very long.. she has rolled 5 times over the last 13wks but nothing consistent... but she's very strong so it's only a matter of time. It will happen all in good time.....

Try not to listen to what others say. Trust your baby girl. If she's happy and healthy and enjoying herself, then the rest will follow..... one day she'll surprise you!