Procedure stop executing

I have stored procedure:

CREATE PROCEDURE [dbo].[mysp]
@saID INT
AS
DECLARE @msg VARCHAR(4000), @message NVARCHAR(255), @counter INT

BEGIN TRY
 SET @tranCounter=@@TRANCOUNT
 
 SET @message='SA ' + CAST(@saId AS NVARCHAR(10)) +'  
 started by '+ CAST(@@spID AS nvarchar(10))

 EXEC xp_logevent 60000, @message, informational

 IF @tranCounter=0
 BEGIN
  BEGIN TRAN
 END

 UPDATE dbo.myTbl SET i=2 WHERE idN=10 AND i=1;

 IF @@ROWCOUNT=0
  RAISERROR ('There is no active alignment.', 16, 1)

 INSERT INTO dbo.myTbl
 SELECT ....
 
 SET @counter=@@ROWCOUNT

 SET @message='SA '+ CAST(@saId AS NVARCHAR(10))+':  
 Orders were reduced('+ CAST(@counter as   
 nvarchar(20))+')! '

 EXEC xp_logevent 60000, @message, informational

 MERGE dbo.myTbl1 AS t....
 
 SET @counter=@@ROWCOUNT

 SET @message='SA '+ CAST(@saId AS NVARCHAR(10))+':  
 Stock was increased('+ CAST(@counter as   
 nvarchar(20))+')! '
 EXEC xp_logevent 60000, @message, informational
  INSERT INTO dbo.myTbl2
  SELECT ....

 SET @counter=@@ROWCOUNT

 SET @message='SA '+ CAST(@saId AS NVARCHAR(10))+':  
 Stock for DD was reduced('+ CAST(@counter as   
 nvarchar(20))+')! '
 EXEC xp_logevent 60000, @message, informational

 EXEC @counter=dbo.p_stock_alignment @saId

 SET @message='SA '+ CAST(@saId AS NVARCHAR(10))+':  
 Stock was aligned('+ CAST(@counter as   
 nvarchar(20))+')! '
 EXEC xp_logevent 60000, @message, informational
 ...
 ...
 ...
 IF @tranCounter=0
  COMMIT TRAN
  SET @message='SA ' + CAST(@saId AS NVARCHAR(10))+':   
  Was successfully finished!'
  EXEC xp_logevent 60000, @message, informational
  RETURN 0

END TRY
BEGIN CATCH
 IF @tranCounter=0 AND @@TRANCOUNT>0
  ROLLBACK TRAN
  SELECT @msg=ERROR_MESSAGE()

  EXEC msdb.dbo.sp_send_dbmail @profile_name='sql mail',
  @recipients='myemail@gmail.com',
  @subject='subject',
  @body_format ='HTML',
  @body=@msg
			
  SET @message='SA ' + CAST(@saId AS NVARCHAR(10))+': 
  There was an error:'+ CAST(@msg AS NVARCHAR(200))+'! '
  EXEC xp_logevent 60000, @message, ERROR
  RAISERROR (@msg,11,1)
  RETURN -1
END CATCH	

Inside this procedure i execute in transaction many updates and inserts and every one is logged.

If I execute this procedure from SSMS(without outside transaction, so @trancounter would be 0 inside procedure), it is always successful and works less than a minute.

If i execute this procedure from application(web page, IIS 8.0, also without outside transaction), the procedure never ends successfully. It sometimes finished at step one, sometimes at step 5, but never ends, always is stopped somewhere in between. And i also never get an error message.
So, catch is never raised and transaction is always rolled back (I guess, since there are no changes in my tables and there is no active transaction If i execute DBCC OPENTRAN)

It looks like that there is auto abort of transaction  (XACT_ABORT is default ON for connections) and there is no error message, as i can't find anything in log and since I don't get error message the catch is also never raised.

Maybe IIS close connection or something similar after some time - but all settings i have found are more than a minute.

How can I find out what happened, why procedure never ends?
That started to happens when we moved to new server, windows 2012 and sql 2012.

Any idea?