At least Italian and French have an idiomatic way to say "I have only one friend":

• Non ho che un amico.
• Je n'ai qu'un ami.

Finnish has the same thing: "Minulla ei ole kuin yksi ystävä." I can't think of a parallel way to phrase it in English. ("I have but one friend" is perhaps closest.) Is there something comparable in Latin?

I can express the same though in Latin easily enough: unum solum amicum habeo or similarly with possessive dative. But this is structurally quite different, and I am specifically after the structure. Is there something like non habeo quam unum amicum, which corresponds quite literally to the three ones given above? (If you add a plus before quam, the syntax seems to work out, but I don't know if the Romance versions used to have such a word.)

What would be the closest Latin equivalent to the construction in Italian and French? I assume a similar thing is found in many Romance languages and they descend from Latin. The closest I can think of is nihil habeo nisi unum amicum, but perhaps there is something closer.