Which itr?

You nee to file ITR-2. even capital gain not made. show the transactions with calculation in ITR -2

i have pension that means itr 2?

Pension also comes under Salary Income only. you can file ITR-2 only

but i have filed itr 1,so what to do now?

You can revise the return  u/s.139(5) through ITR-2,since it is filed with in due date ,you can revise 

can i show this transaction in next year ITR instead of taking it this year and let itr1 run as it is?

Current year transaction cannot be shown in next year return. 

My suggestion is  to file the revised with showing the transactions. because Income tax department is monitoring the high value transactions in the bank accounts and through  some other sources.

If you shows in the return, no problem will arise, otherwise  department may send notice for explain these transactions.

Since you are not having capital gain on that transactions, better you can revise the return

one last query i have not taken the possession of this flat till now as it is not ready, does that affect anything?

It  will not effect anything. because it is not involve any tax liability , My suggestion only avoid  if any future questions from Income tax department. nothing else..

I mean that " not being able to get possession of house i purchased with the gain  not put it to be shown in next year itr?

In  case ,the sale of existing house happened this year and also  you have already purchased the property , only possession pending then no problem

But the sale of property happend this year and you want to purchase and possess the property next year then mandatory  to show in the return to claim exemption ( also the sale proceeds need to be deposit in the Capital gains account maintained with any bank