The hormonal changes of pregnancy and breastfeeding may interfere with the results of laser hair removal in several ways. There is a concern about potential hyperpigmentation that is more likely under the influence of hormones.
Also, the way the hair grows is affected by any hormonal fluxes, so the procedure may not be as effective during those times.
The numbing creams used during laser hair removal can potentially be absorbed into the blood stream and delivered to the baby via breast milk. Even though the likelihood of this happening is small, there have been cases of application of topical anesthetics to large enough body surface areas that the absorption of these led to severe medical complications, even death. So we know that these medications are absorbed through the skin.
I would advise to wait with laser hair removal until after your are done breastfeeding.