In my opinion the important factors in the application for settlement visa is proof that it is a genuine relationship and you have the finances and accommodation to support your partner without the need for public funds.
Regarding the proof of relationship this is to be shown by the evidence that you will provide in the form of photos, travel itinerary, hotel bookings etc.
With reference to the financial requirements, the need for 6 months of bank statements and pay slips is to show that there is regular money going into an account.
As each application can be slightly different the need for the letter of support is essential to outline your particular circumstances.
In your case even though you say you married quickly, the fact that you are still married 3 years later should show the relationship is real.
Explain in your letter of support about your savings and income and also provide the projected forecast for your business, from an accountant if possible, and I feel this should be sufficient to show that you have the means to support your family.
I wish you all the best in your application and hope that you will be together soon as a family here in the UK.
