And yes its my first baby
If its too early in the pregnancy maybe he doesn't want to cause more issues by doing the U/S you'll have to do an internal one if it's early and maybe he doesn't want you to do one yet. I know my drs office won't do one before 8 or 9 weeks... just to be on the cautious side.
That surprises me your doctor didn't do an u/s. I'd be requesting it nicely but firmly...
Is this your first baby? How far are you? Important to know. If your early it was probably implantation bleeding. As long as you are not cramping or passing clots with a lot of blood you should be fine.