To answer your first question above, "Is it bad to use 2 nebs to break asthma attack?" I would have to say it depends. A majority of asthma experts might simply give you a flat out "Yes! If you have to take back to back nebs this is a sign of worsening asthma and you should seek help!" In fact, for 90% of asthmatics I might give just that advice.
However, I'm aware that there's a 10% minority of asthmatics who do not respond to conventional asthma theories (your hardlucks). So long as you are working with your doctor and doing everything to a tee to make your asthma better, and you continue to need your asthma medicines daily, this is okay.
2 reasons: 1) asthma medicines are proven safe and 2) using your asthma medicines as you describe above is far better than making daily trips to the ER or doctor's office. If you need back to back treatments from time to time, go for it. However, don't do this in secret. Make sure your doctor is aware of what you do at home.
Still, at the same time, continue to work with your doctor, and doing your own research, to find ways (or ideas) that will help you make your asthma better -- which seems to me what you are doing.
What I write here is based on my own experience as a hardluck asthmatic, and my interviews with other hardluck asthmatics.
The problem with managing your asthma this way -- and I experienced this -- is you might have a tough time determining when exactly to go to the ER, or call your doctor. If those two treatments don't break your asthma, or if you need more than YOUR normal # of puffs on your inhaler, you should seek help.
Don't give up the fight to better your asthma because there are many options to help you get your asthma under control, it's just a matter of figuiring out what works best for you.