My peak flow is usually 500 or 510. There are times when I feel as if I'm having asthma symptoms- slightly wheezing, short of breath, tight chest, and my peak flow is still at 490 or 500. I usually end up taking my inhaler anyway, bc the symptoms are uncomfortable and I start to panic as I don't want to have an attack.

Is it still asthma if peak flow is good? Thanks.

Toss the meter. Go by what you feel. I did and am glad of it.