Hello and welcome to the forum.
I read your post and I have to say that in your situation, I would not be looking to get married at this moment in time. It sounds as though you are, or very nearly on your knees with the jealousy and her general insecurity. Four months is not an insignificant amount of time for her to get used to the UK and also to be re-assured, constantly by the sounds of it, by you and your actions.
I'd like to say that things would get better by being married, but my gut feeling is that her jealousy / tampo would continue. Don't forget, ALL couples need to have some time away from their partner ie hobbies, social groups etc. It's a healthy part of being in a committed relationship. Can you honestly say that the way things are at the moment you would feel happy for them to continue as they are for, maybe for years to come?
I realise that as far as the fiance visa is concerned, time may not be on your side with regard to the wedding, but you have the rest of your life to consider. Think long and hard....................
