I am in Disbelief !!

After 3 years of having my Daughter I got a BFP ! I am seriously in disbelief and won't believe it until I have an ultrasound & confirmed with my doctor 100 % and the reason why is because 2 weeks ago exactly on Monday 4/24 I did blood work to see if I was pregnant and the results came back negative & i would of been 6 weeks exactly when I did the blood work . I was suppose to get my period on 4/17 and never did .. took so many test & different kind Almost every other day and all were all negative . My last negative test was on 4/29 right before our vacation which was a week.So I just gave up that whole week we were on vacation , I didn't think about it or talk about it at all with my husband it was a stress free vacation which was much needed for us .We just both pretty much just said we are giving up on trying and if it happens it happens .. So now fast forward to last night . I was watching a movie with my husband and I just happen to have a really bad cramp on my right side & I had moved wierd and my husband ask what it was, I told him I was having a cramp & he is the one who insisted to take a test ( this was 9 pm and I seriously didn't want to see another negative test knowing it was that late  ) so I still said to my self why not so I grabbed the one dollar test that I had extras (cause why not lol) and I went to the bathroom and really wasn't expecting anything to be honest , but when those two lines popped up I just starting crying and I couldn't hold my self , it's been so long since I seen two lines .. so my husband comes running into the bathroom asking me what happen and I couldn't get my words out , he saw the two lines and just hugged me and kissed me ( I have been planning for years to surprise him if I got a positive but I guess that just didn't happen & I am even happier to be honest how it did . But any how I took another test this morning (FMU) First response & I got my lines again .. After everything and having two positive test and so many negative i am still in disbelief ( since I didn't go through this with my daughter when I found out I was 6 weeks with her ) So I am waiting till 9 am to call my doctor to set up an ultrasound . So I will keep you all updated on that .. 
I was just wondering if this has happen to anyone else before , negative blood work and all negative test & then BAMM BFP . 
Here is some of my negative test (that I didn't delete ) and then the positive 
Update : I have another blood work to do today . My doctor told me I couldn't do an ultrasound until 10 weeks which I would have to wait another 2 weeks or more depending how far along I real am .. I am just so nervous and I hope it all goes well and I get my positive with my blood work . They should be calling me with results first thing in the morning .. 
UPDATE2 : THE BLOOD WORK CAME BACK AND I AM PREGNANT! I AM SO HAPPY I CAN't BELIEVE IT , IT TOOK 3 YEARS WITH THE FIRST NOW AGAIN ANOTHER 3 YEARS .. the doctor did say that I must of ovulated really late so that's why everything was coming out negative .. but thank you all who congratulate me .. ALL OF YOU DONT GIVE UP AND IT WILL HAPPEN TO YOU ASWELL . BABY DUST TO ALL AND WISH ALL THE BEST OF LUCK WITH EVERYTHING ❤️