Hi J.. My son was diagnosed with asthma at 14-months old. I felt so bad for my baby to have to use a nebulizer and he cried at first. The doc said crying is good, he will breathe in more of the medicine and breathe it in deep. He got used to it, but what helped for him was to put on a favorite TV show or movie to distract him a bit.
We also had an extra mask that we put on a teddy bear so that he was getting his treatment just like my son. At 14-months he thought this was great that teddy sat with him and got his medicine too!
In my opinion you would be doing more harm by not "restraining her" and getting the medicine in. As long as you aren't hurting her, letting her fuss and cry isn't the end of the world. She will get used to it...and so will you! I sometimes cried right along with him, but I knew it was for the best.
I do believe you need to use the mask. Just holding it in front of her will not "force" her to breathe in the medicine.
My son is now almost 12 and is off his daily medicine and only uses his inhaler before heavy exercise. I was told that getting asthma that young is actually better than getting it as an adult as the child may outgrow it and the adult may only get worse.
P.S. Reading someone else's post reminded me that I always let my son turn the machine on too. That way he had control of something. I believe part of the fear was that 10 years ago these machines were awfully loud. I do believe they have improved on them, in size and sound, and hopefully they aren't so scary!