Since becoming pregnant, my nipples have turned much darker. Will this keep me from breastfeeding? Is this normal?

This is normal. Darkening of the nipples and surrounding area called the areola is completely normal in pregnancy. A dark line (the linea nigra) may also appear down the middle of the belly. The color change in pregnancy is more dramatic in darker skinned people. This is all normal and will not affect breastfeeding in any way.
Normal. It is normal for the nipple and the aereola (the area around the nipple) to get darker during pregnancy and will not hinder breastfeeding. In fact, some believe it helps a newborn find the breast because they see contrasts, not colors...The darkening makes it look like a bull's eye.