L.S.
Prolactin can seriously impede a woman's libido, ability to lubricate and also ability to climax. Many of my long term nursing friends have had this issue...it is VERY normal for nursing mamas.
I also want to commend you for continuing to nurse...it is the very best gift you can give to your little girl.
Somethings that have worked are longer foreplay, really good lube my midwife suggested Astroglide, making sure you are very hydrated and having a glass of wine (to relax) before becoming intimate.
also if you have had any tearing or an episiotomy...you can expect this issue to be a worse
with light
-L.