BIG PROBLEM transaction log does not shrink after full database backup

Hello

I have a BIG PROBLEM i.e.MS sql transaction log does not shrink after full database backup.

I am only few days before going live . the server is running half year.

I would like to switch off transaction log on development and shrink with full database copy or transaction log backup(or anyhow)

I am performing backup with Enterprise manager.

I also restarted server few days ago. but still the transaction log does not shrink after database backup. I tried also only transaction log backup.

Please help me