snorting heroin how much do i need

i have snortet two small lines. had one waitet 10/15minutes felt nothing so i had the same amount and now its been another 10/15 min and i dont really feel anything so now i want to ask how many mg/g you would suggest cause i dont want to od but obviously want to feel it

i've been taking and shooting morphin pills. i would shoot 150-250mg of those but i want to quit the needle so i got heroin which i've shot up once but very little and weeks ago. do u think smoking would do more? if so how many mg/g there?

maybe some one could give me some reference or idea. doesnt have to be exact of course just somehing vague or a number which i really shouldnt go over would be just fine too

i hope for answers thanks in advance