problem with iphone 4s wifi, please help :(

Hi all, I am new here so forgive me if this is in the wrong section.

I have a problem regarding wireless internet that is frustrating me to death, i would really appreciate your help!

I bought my 4s in December, for say, the first week or so, the wireless worked fine (i have cable with a wireless adapter thing attached to it) then for some stupid reason, my connection just started to go slow! i didnt tamper with any settings it was literally all of a sudden.

it says i am connected, but the pages just either dont load or they load really slowly.

Then the other day, my wireless decided to work again! And then it stopped about a week later. I am so confused! I didnt have this problem with my previous iphone, and my laptop seems to connect fine to the wireless, so i know its not the wireless connection.. it is something to do with the iphone. i have tried restaring the network settings, hell i've done pretty much everything i can think of. but this is my last resort and i hope someone can help!

thanks,
natasha x