Does the pregnancy still go on after the misscarriage

On 19Jan I found I was pregnant also found few blood dropped, At 21Jan Iwent to my GP for blood test and have a Ultrasound scan from vignia, the blood test result is pregnant. After 21 Jan I found I bleeding very heavy just like the period for 4 days( usually period last for 4 days). 27Jan went to my GP , the Ultrasound report: there was Cell inside but was empty then blood test again to make sure pregnancy drop , the result the HGC low my GP told me was negative and I did the Home Pregnancy test at home the result was negative. A week after Home Pregnancy test was still negative.18Feb Home Pregnancy test was positive again.

5th May Ultrasound , the outcome was my due date is 26 October and surprise me that my start day of Pregnancy was19 Jan(15 weeks pregnancy currently).
I couldn't understand I thought this is an another pregnancy but not the same one or the next one Please help

Pregnancy's are dated from the first day of your last menstrual period, so when you find get a positive pregnancy test your already around 4 weeks pregnant. So with your first pregnancy, you were 4 weeks when you found out, so your 'start date' (first day of your last menstrual period) was 19 December. Unfortunately you lost that baby at four weeks, but you got pregnant again straight away! I hope this helped, sorry for your loss but best of luck with your new pregnancy :)