Almost all of it has come from automatic payouts from this pool -
http://bcn.extremepool.org/#, mining using one 270 and CPU - payments range from 60 to 100 or several hundreds of BCN. Previously I had 5k BCN which were withdrawn from minergate and 2 hours ago I cleared some 62 BCN from there, to level my balances there - not sure did they arive since it's a small amount.
So that is the reason. You have a lot of small inputs that is why your transactions sizes are out of limits.
I guess you can transfer your coins to another wallet (in order to generate bigger inputs) and use it instead.
A lot of users suffer from this problem caused by weird pool's payments