Liposuction scar tissue and pregnancy. Will this cause complications when my belly starts to grow?

First of all, congratulations on your pregnancy!
In most people, liposuction does not cause a significant amount of scar tissue; however, when scar tissue *does* form after liposuction, it is confined to the "fat layers" (the so called "subcutaneous tissue") between the abdominal wall muscles and the skin. Scarring in these tissue layers is highly unlikely to cause a problem for future pregnancy. In order to constrict the enlarging abdomen, scar tissue would need to be continuous around the entire abdomen, and this simply does not occur after liposuction. So your liposuction is unlikely to affect your pregnancy.
On the other hand, your pregnancy will certainly affect the abdominal contour you achieved with liposuction. Most obviously this is caused by stretching of the abdomen during pregnancy, as the body produces hormones which "relax" tissues, including ligaments, muscles, and joints. The combined effect of this plus increased pressure from the enlarging uterus may cause loosening of the skin, subcutaneous tissue, and abdominal muscles. I would recommend waiting at least six months (and perhaps as long as a year) after you deliver, to allow for these changes to stabilize before seeking further aesthetic treatment. In the meantime, your OB/Gyn can counsel you on the best approach to diet and exercise, to as to maximize your body's ability to respond to the changes of pregnancy.
Wishing you good luck, good health, and a safe delivery!