Sadly you may need to go for an extension.
I would suggest, go for postal application and if you are lucky (or unlucky??!?) , and your decision got delayed by 2 months, then vary the application as explained here (see section "Varying an application") by paying the additional fee.
https://www.gov.uk/government/uploads/s ... .0_EXT.pdf
You cannot apply for ILR more than 28 days before completing the qualifying period.
When was your first Tier 2 visa issued (inside or out of UK)? If it was issued out of UK, you could count the days between the "Validity start date" and "Date of entry in to the UK", as long as this is no more than 90 days.