is it just to early to see on an ultrasound?

[i_am_who_i_am]

I recently found out I am pregnant, August 26 was when I did a home test 2 of them actually and I thought I had seen a very very very faint line but my boyfriend thought I was crazy until I did the second one and he seen something very faint also. So I went to the doc that night and had a test done and it came up negative. Then the next morning I did another home test and this one also came up a faint poisitive but more obvious this time so again I went to the doc that day and again their test came back negative. They ordered a blood test be done and sure enough I found out I am pregnant. Then lastnight I went to the hospital with some cramps in my uppser abdomen that honestly I think was gas pain because it only hurt when I would sit certain ways and I was gassy. The docs there ran a number of tests and said my hcg hormone level came back as a 150 which they thought was kind of low considering they thought I was 7 weeks along based on my last period. They did an ultrasound and found no baby but did find a small spot on my ovary they said ccould be a cyst that is typical of prgnancy or a etopic pregnancy, They really have no idea whether its a etopic pregnancy or just to early to see the fetus on an ultrasound. Thhey were unsure of the etopic pregnancy because I was not in a lot of pain and there was no bleeding, They sent me home and told me to return in two days to do another blood test to see what my levels are doing. But when I got home I got to thinking. I forgot to tell them that my menstural cycles are anywheres from 40 to 50 days and when I calculate that I would only be about 3 weeks from conception. Just a little history here. My last menstural cycle began July 13 2010 and I went to the hospital on September 1st 2010 and at that time my hcg was 150. But like I said my cycles are anywhere between 40 and 50 days apart. I was just wondering if anyone on here had some insight for me. I am terrified of an etopic pregnancy. The doctor told me it may just be too early to see the baby and had to consider etopic pregnancy as part of protocal to cover thier own buts basically make sure they dot all the i's and cross all the t's. I have been experiencing mild lower back cramps and the odd random cramp in my belly but nothing really painful.

[StressheadNZ]

Hi there, I've had 2 ectopic and never had any symptoms until I bled internally and was rushed into hospital for surgery. Usually an ultrasound won't see anything until your hcg levels are at around 1300-1500. You should be getting blood tests every few days to see wether your levels are doubling every 48-72hrs which would indicate a normal pregnancy. With my ectopics, my levels were rising but not doubling. They need to watch your levels closely until they are high enough to see on u/s.  hopefully you get positive results!

[SHVEPS]

I think that because your periods are so far apart, it is quite likely that you ovulated late and you are not as far along as 7 weeks, which would make it too early to actually see a fetus. Did they see a gestational sac at all on the u/s? That is usually the first pregnancy tissue visible. In any case, it is a waiting game now to see what your hCG levels will be next time to make sure this is a viable pregnancy.
I've never had an ectopic pregnancy, but I have heard that it is really painful. The mild cramps you are feeling are very normal in early pregnancy, it is the uterus stretching.
Hope everything turns out great!