I'm in a tricky spot - having to make a decision which could completely change my life but being unsure what the best thing is to do.

Essentially, for those who don't already know, i'm in a long-distance relationship with a girl in america. She has 2 more years of university to complete, and then she is planning to move to london. I finish my masters course at the end of september, and currently have no ties keeping me here afterwards (this could change soon as I am looking for jobs and a place to live in october).

The plan at the moment was for me to go visit her for a few weeks in october, and then come back to work and live in london and occasionally visit each other until she moves here permanently.

I was looking into flights for october last night, and realised before i book them i need to work out how long i am staying for. Obviously the longer the better, but she will be studying and working part-time, and i won't have anything else to do so if i want to stay for anything longer that a couple of weeks then maybe i should think about getting a job to occupy myslef/earn some money.

The two options i have before me are:

option 1) get a job lined up in london, get a place to live with my friend, go see sarah for a few weeks and then visit occasionally thereafter for the foreseeable future until she moves to london in 2 years.
PROS- no big risks, career development
CONS- only seeing sarah for a few weeks every few months
option 2) move to the states for the foreseeable future, get a job of some kind and stay there for 2 years until sarah has finished her degree and then (assuming all is equal) move back to london together.
PROS- be with sarah all the time
CONS- big risk. no job or flat in london to come back to. career possibly on hold, unless can find relevant job.
its a tricky one. the way i see it, after i finish my degree i no longer have any real need to be in london, so am free to move to be with sarah. also if i was just 'visiting' for an extended period of time it could be pretty boring as sarah will be studying and working part-time, so i might as well be too. but then it is a big step to take, and if it doesn't work out i have to start over again in london, try and get a job from scratch and find somewhere to live on my own as my friend will have sorted himself out.

i know its a decision only i can make, but does anyone have any experience of similar situations, or advice they can offer? i'm really struggling here :(

thanks