Hello, a peak flow meter is not the answere.
Ask your family doctor to refer you to a resperologest.
He will do a series of test to measure your lung capacity.
They will do a blood gass test on you to get the exchange rate of oxygen, this is by taking blood from you artery in your rist the same one you feel for your paluse, not a vain.
Lennie

I have type 2 diabetes ,copd and all three that go with it also severe Osteo through-out my body , still smoke smoke , quit for 2 yrs. and felt terrible and sick more often , at this point in life at 71 i'm going to enjoy myself n, I am in God's hands. I'm not on oxygen as of now.. Everone have a breathe easy day and God bless.

When thay check my blood thay go deep vain in wrist .you will have tank test it will give them better reading hope you have better days to come i have some good days i breeth throu nose and been so strest had a crafty cig which ino is bad but relaxes me

You Want to buy and oxometer I did and I test my own levels It only cost £7.98 The best thing I ever did If it drops below 90 you need to go to the doctor him and tell him Some time they just brush us aside Hope this helps

You could go to the lung ASSOCIATION