TTC, Home Tests Inaccurate?

[MeiTheArtist]

The first time I was pregnant, it was unplanned. I /knew/ that I was, but the home tests I took [four of them] all said negative. I went to the doctor and I actually was pregnant, gave birth to a baby girl.
Here I am 2 years later, and I /know/ that I am pregnant. I just do. I've had basically almost every symptom you can think of, yet my home tests still are saying negative. One even gave an extremely faint positive before that same second line actually faded completely. I am 6 days late on my period, I haven't had any spotting or any sign of my period coming anytime soon. I'm frustrated and I'm tired of this being an issue. The doctor I saw when I was pregnant the first time actually said there are some women who just can't take home tests because they'll always be invalid, and that I might be one of those women.
Here are my symptoms:

-very slight abdominal cramping [most of it is gas, I'll be honest]
-varying degrees of nausea throughout the day, strongest during morning and evening and around strong smells
-smell sensitivity [very strong]
-food averson/cravings
-hot and cold flashes
-increased need to sleep
-appetite change [I've become hungrier than normal]
-increased bathroom breaks
-constipation [blah, sorry, I hate listing this one]
-bloating

I have been trying for a child. I've kept track of my periods, my ovulation days, whatnot. I know it's not good to just reach out to people on the internet, but I need some advice. I am unable to visit a doctor, as they are closed today and this weekend. I did ask a nurse about this the last time I was pregnant, and she has said that I may be simply sensitive enough to changes in my body that I know something's different a week or two before the change is noticed on a test.
[I was actually only 1 or two weeks pregnant the first time when I found out, and I had the same strong symptoms.]

[Raerae336]

I recommend using a First response early response pregnancy test. They are the only tests that have been positive for me with all three of my children and all three of my m/c while every other test including the doctors were negative, and i had to get a blood draw. They detect hormone levels as low as 7.5. If you're negative on those i would suspect you're not pregnant and something else is going on. I say this because if the hormones are strong enough in your system to cause symptoms, then they should be strong enough to register on a pregnancy test as sensitive as first response early response.

[Jesso24]

Sit tight x
You will find out whether you are pregnant soon enough