Calculation SLA with some data

Hello everyone. 
I'm a newbie at power bi and still learning everyday through youtube and this forum. 
I have to make a rapport to show sla, in this rapport i have to display :

sla each month  (sla achieved / sla achieved + sla breached)

sla target at 90%

number of sla achieved per month

numer of sla breached per month

this is a sample of what i already did but i have some problems.

the SLA calculation runs to the end of the year while i want it to stop at the current date (or latest date in the import) 

the SLA target runs to the end of the year while i want it stop at the current date (or latest date in the import)

the main problem is that in certains month, there is no sla achieved and while the formula is achieved/achieved+breached i have the result "empty" instead of 0.
I'll write all the formula i usa to show you how it looks like :

Display achieved and breached per month:

1. OLA Achieved = IF('SLA(OLA)'[Stage]="Achieved", FORMAT ( [Closed at], "YYYY/mm" ))
2. OLA Breached = IF('SLA(OLA)'[Stage]="breached", FORMAT ( [Closed at], "YYYY/mm" ))

 

Display SLA calculation :

ola calcul = 0+CALCULATE(COUNT('SLA(OLA)'[Stage]),'SLA(OLA)'[Stage]="Achieved")/(CALCULATE(COUNT('SLA(OLA)'[Stage]),'SLA(OLA)'[Stage]="Achieved")+CALCULATE(COUNT('SLA(OLA)'[Stage]),'SLA(OLA)'[Stage]="Breached"))

 

my formula to display a line at 90% between the first date and the last date is not working for the moment

Thank you in advance