First off,ALL pregnancies are different!
With my first son I was so sick at the very beginning I thought I was gonna DIE,but it past quickly(within 6-8 weeks),I think I may have gained 10 pounds with him and the rest of the pregnancy was uneventful.My second pregnancy was shear JOY,no probs what-so-ever.Now that being said,my third pregnancy(14 years after my second!)I was TOTALLY miserable the entire time..tired,ILL all the time(not throwing up,just SICK),achey(sp) and I too got very light headed alot!!IF this is THAT much of a concern to you,DO NOT hesitate to call your OB,THAT is their job.And yes a lot of women have the same probs you are describing,but if it is something that has you concerned or seems out of the ordinary TOO YOU,call the doc.I don't think my doctor ever slept the whole time I was preggers,and not because of me,but WHENEVER I called her with a concern,day or night(I only called once at night!),She was the one who called me back and usually within 30 mins and SHE was the one who reassured me I wasn't a prob/nutcase and that was what she was here for!!!!I couldn't Thank her enough.
Also a little hint..the younger you are,the more doctors try too "shrug" things off,no what I mean.
All-in-all I think you are fine,but at the beginning the office visits are so far apart,I think we need a little assurance-reassurance everything is going fine.Good Luck and God Bless,R.