Rashi (from Nidah 38b): Tekufos implies at least two, and Yamim implies at least two (it was six months and two days). This shows that one who gives birth after seven months, they need not be full months (even part of the seventh month counts like a month).

Radak: She became pregnant beforehand. We find that the prefix Vov [with the future tense] can refer to past [participle, i.e. before what was just said], e.g. "Katzafta va'Necheta" (Yeshayah 64:4; Hashem became angry after we sinned), "va'Yibak'u ha'Mayim" (Shemos 14:21. This was before the sea floor became dry.)

Rashi: She was Sho'el (requested him) me'Kel (Malbim - directly from Hashem, not via intermediaries). Radak - the name contains the letters of Sha'ul, and me'Kel. It is as if she said ¹ Sha'ul me'Kel.