Remind her that she's luck you aren't in Canada? I'm just starting back on Monday after 10 *months* paid off, never mind weeks. Reminding her that your entitled leave is the shortest in the Western world might point out, politely, that asking you to come back early if you don't feel up to it is egregiously unfair.
Honestly, at 5 weeks with my first, my episiotomy wasn't even healed. Where I live, I would need a note from my Dr to return to work before 6 weeks, and I would have to prove it was an extreme hardship to myself and my job. I believe an MP needed one once to go vote in an important issue- and even that had tongues wagging mildly. 6 weeks is considered minimum healing time! You need at *least* that long normally to make sure you are not having any post-partum complications.
I am sorry, OP, for somewhat hi-jacking with a rant, but I am very upset on your part that you are being asked to cut short what I consider to be an inhumanly short maternity leave period. Please take the whole thing and let yourself heal and bond with your babe