We are also worried that if we get rejected and then get married and apply again that they will think its a fake marriage, purely for visa purposes
With the recent changes to the visa application laws (on this site in another post of it's own) i would think (but am not suggesting either way!!!) that for the time being to stick with your current application.
There are plenty of opportunities along the process to 'beef up' your case. You have already provided additional information,
IF they call you for an interview then you have another opportunity to answer any concerns they may have. In the very WORST CASE scenario that you are denied, the appeal process, although terribly draining and lengthy, should see you finally approved with a good genuine and strong case.
If i was in your position, is there any possibility to collect information/evidence etc to prove the continuing genuine-ness of your relationship so you can be fully prepared for any news? At the very least, should London not require it then you have kept your mind busy and can have a ritual burning of said collected information!
All will be resolved one day - hopefully soon.