stuck... Plateau??

hey all... I need to throw a question out to you all....

first off i'll tell you my story for the last couple of weeks... went on holiday, ate the wrong foods gained 7lbs, first week back and on 1200 cals i lost 6lbs, 2nd week on same cals lost 2.5lbs, this week so far only had one bad meal wednesday (cheat day)and have otherwise been really good and currently showing a 3lb gain ( gutted to say the least....i know this is probably water weight so trying my hardest to get if off. I'm still on 1200 cals or near enough ...and trying to do light exersise most days

My question to you all is... where do i go from here, i seem to be fighting these same few lbs they keep coming and going week in week out and i'm not moving anywhere fast (

So... should i stick with 1200 cals and eat my exersise cals back so my net cals are around 1200 ( currently they are around 1000-1100) or should i up my calorie goal to lose 1lb a week and then still eat my exersise cals back?

I am also thinking about a low carb diet after reading previous member posts on here, but how low do i need to go? should i halve or quarter the figure MFP gives me?

Any help or advice appreciated thank you all,xx Also any advice on how to shed water weight quickly would be really handy too )

oh.. and i'm 5.5'
current weight is 147lbs
goal weight is 126lbs ( hopefully by end of july)