Concerning the creation of an equitable trust, the application of equity in such "mortgage cases" surely centres round whether the claimant has “acted to his or her detriment or significantly altered his or her position” in reliance on the express common intention. A bit similar to the Scots statutory provision of "economic disadvantage".
I can't see how the OP has suffered a detriment, now that she has had her £2000 returned to her, as she would have had to pay for somewhere to live and bills anyway. She hasn't, for example, been persuaded to sell her own property and invests the proceeds into renovating her partner's home.
So the courts allow for a person doing certain things in a relationship out of love and affection which are probably a bit trivial and personal to be claimed back when that relationship breaks up.
So in Eves v Eves, the Plaintiff had made a "very substantial contribution out of her earnings after to the housekeeping and to the feeding and to the bringing up of the children which enabled the defendant to keep down the instalments payable under both mortgages out his own income and, moreover, that he could not have done that if he had had to bear the whole of the other expenses as well."
In Gissing v Gissing, a married couple had stayed in the marital home for over 25 years...its not just a matter of picking out which bits of cases suit you best, but of understanding the whole body of common law on the point. Whether that body of common law involves the application of equity or not.
Heres a summary: www.familylawweek.co.uk/site.aspx?i=ed34330