Apps Don t Always Load-Phone or Service Issue iPhone

I have the iPhone 4S (AT&T as my provider) and awhile back when I did the software update iOS 5.1.1, I am now running on 4G. Now, I've heard many things about 4G - that it doesn't make your phone load any faster, it's not really 4G, etc. However; even with full bars when I try and run my apps (i.e. Instagram. FaceBook, games, basically anything require an Internet connection), it often "times" out and cannot load the app. I also have trouble sending and receiving e-mails, and text messaging as well as with Safari. I have had to turn off iMessaging because it always fails to send. I'll get error messages saying my connection has timed out, cannot refresh feed, server cannot be reached.. Obviously when I am connected through Wi-Fi, I have no issues but when I am only connected through 4G/Edge. Has anyone ever encountered this problem? Is this a service issue with AT&T or is it my phone that I will need to bring in to Apple to have them check out?