FIRST EVER BFP!!!

My fiancé and I have been together for 10 years, I'm 25, been engaged for the past 5, and been ttc for the past 4. He has a 12 year old daughter but I have never been pregnant. We went to the hospital Friday because I was feeling dizzy and to our surprise, we found out we were pregnant. I have my first doctors appointment in 2 days, and it looks like I'm 6 weeks based on the first day of my last menstrual which was May 9th to the 13th but they want to do blood work and run some tests because I had another 5 days of another menstrual from may 25th to the 29th and she said the tests wouldn't be positive if that was when I got pregnant. So she said looks like our conception date was May 18th (our anniversary) ☺️☺️ and my due date is February 13th, 2018!!!