Do I really have unlimited data?

I have t-mobile and signed up for unlimited data and when I use my tmobile app for my iPhone 5 it says I have evrything unlimited but today I was watching a movie online using my data and received a message saying I have exceeded my data plan 4.5GB and my speed is terrible and it says LTE on my iPhone.

I'm a current T-Mobile user and have a Galaxy SII.

ALL T-mobile plans have unlimited data, but depending on the plan options you get they will throttle you at 500mb, 2.5gb, or unlimited. Once you are throttled your speed is drastically reduced and if you are going to use that much data every month then you will want to opt for their unlimited unlimited plan.

My guess is you have their 2.5gb plan, and you have exceeded it (by a great amount if you are at 4.5gb for the month). If you plan to use more than 2.5gb per month then the unlimited unlimited data plan is $10 more.