welcome to HCM.
Earliest you can suspect of pregnancy
is when you miss your regular period. Earliest way to detect pregnancy is by serum B HCG
test. One week later it becomes detectable by urine pregnancy test. These tests detect pregnancy much before you start having symptoms of pregnancy.Constipation
is not a sign of pregnancy. Internal ultra sound
is done in the first three months of pregnancy, after that generally it is done transabdominally.
Wishing you all the best and hope you are pregnant.