don't know if I got pregnant before my period

[I'mgaj]

I'm very confused about when I got pregnant. I had sex with a guy on Aug.25 and he (pulled out). I also had sex with my boyfriend that last week of Aug.  On Sept. 2 I started my period. After 3 days of my period I continued to have sex with my boyfried. I missed my period in Oct. and found out I am pregnant. On Nov.1 I had an ultrasound done. The ultrasound said I was 8 weeks and 6 days pregnant and the baby measured avg. 23mm.  I would like to know how accurate the ultrasound is along with the measurements.
If I got pregnant before my last period, then I was really 9 to 10 weeks pregnant. But If I got pregnant after my last period then I would only be about 7 weeks because of ovulation,right? The doctor said I was 8 weeks 5days pregant according to the first day of my last period. When did I really get pregnant before or after my last period? If it was before, could I have been 9 weeks 5 days at the time the ultrasound said 8 weeks and 6days or could I have been less than 8weeks pregnant.
I'm sorry for the confussion but If you could please help, I would greatly appreciate it. My boyfried is so excited, and I realy screwed up by being with that other guy.

[AnnieBrooke]

Hi, Mary, best thing is to take a test.

[mary_gzz]

Ive been trying for a little one with my husband. i had my period June 24th for about 7 days.. Continued trying throughout the whole beginning of July until i received my period again July 22nd for the normal 6/7days. it is now august 22nd and no period. could it be possible that i am now pregnant?

[AnnieBrooke]

Hi, Jelisa, I answered where you posted this as its own question.

[Bird27]

hello my nae is jelisa and im really confused i had sex with this guy on june 19,2015 but we used protection my period came down june 21,15 but on july 2,15 me and my boyfriend had unprotected sex went to the doctor they told me i was 4 weeks pregnant how is the possible wondering if i got pregnant before or after my period

[AnnieBrooke]

Hi, Promise, here is what the conception calculator says for a due date of September 12.  If you got the due date from an early ultrasound, the first guy is not the father, assuming, that is, that you had sex with your boyfriend later on besides the "days later" than "around the end of November" that you mentioned.  How did you get your due date?

First day of last menstrual period:  December 6
Probable date of ovulation:  December 20
Possible dates of conception:  December 16 to 24
Due date:  September 12 (40 weeks)

[Promise2]

I had sex with a guy in November around the end of the month , he used a condom and pulled out , then had sex with my boyfriend days later , I had a period in November and one in December it lasted the normal 3 days my due date is September 12th 2015 when I went to the doctor on January 21st I was 6 weeks , how do I know who's baby it is :/ PLEASE don't judge !