Hi L.
you sound exactly like me -- my 12 mos old daughter won't hold her own bottle either. Being a first time mom I never encouraged her to hold it on her own and now I regret that.
We tried everything, making her hold it, propping it up, etc and she's very defiant and stubborn about it. Yeah, we could really force it upon her, but she'll soon be using a cup (she drinks water out of it with no problem) entirely, so we're not sweating it. I just enjoy the closeness and if she's hungry during the road, I give her the sippy cup or finger foods.
So I'm just concentrating on her learning to use the sippy cup more and more, instead of teaching her to hold her own bottle.
Yes it gets annoying when u have millions of things to do and you have to sit there holding it for them!
So I'd start introducing the sippy cup by putting water in it for now, and she'll eventually transition into using it all the time. But don't sweat it. As my daughter is a year old we're in the process of transitioning her to the cup but again, we're not sweating it and know she'll use the cup eventually!
Relax, things will be fine, before u know it she'll be 20 yrs old and definately not using a bottle!