This thread is kinda sprawling in terms of topics covered so I'll just offer a few separate thoughts. Hope they help. If not, feel free to ignore.
1. A lot of times people 'don't get pregnant' because of spontaneous abortion very early on. It just occurs naturally. No one's fault or anything like that. So it's possible to be pregnant a few days or weeks and then lose it and not be pregnant. If you weren't anxiously awaiting the start of a period, you might not even notice. Also, stress and a trillion other things can delay a period. Also, I'll echo, it's always good to see a doctor to make sure though they tend to use the same 'take home' type tests most of the time. They just do it in the office.
2 I agree with most of the other things that have been said here, but at some point it becomes a lot of mental contortions and excuses to explain in hindsight why a reading was wrong. Which brings me to my next point...
3. People will disagree, but sometimes a reading is just wrong. Tarot's not infallible. Nothing is. Readers/humans certainly aren't infallible. Sometimes cards are tricksy, too. I seem to remember a thread on here long time ago about whether a baby would be a girl or a boy. The person drew the empress, which in their deck actually had the female symbol on it, so the consensus was 'girl'. I think the baby was a boy though. lol (Or at least the sonogram seemed to indicate so. Not sure if we heard after it was actually born.) Tarot is still a valuable tool though that works the vast majority of the time.
4. After many years of round and round with the yes/no thing, including using a simple system for a long time that was very often right, but not always right, here's what I do now. (I only do yes/no questions for myself, so far, btw.) I think about the question while shuffling and then I draw one card. As soon as I see it, meaning the artwork, I go with my gut feeling. No thinking about meanings or staring at the picture to analyze it. Instant gut feeling. Intuition. This method has been right every time so far. I've also found this an accurate method for timing questions. First thing that pops into my head when I see the card turns out to be right. No timing 'system' for tarot has ever worked for me. Maybe it's using tarot to tap into some other ability but it works for me.
5. Don't drive yourself crazy trying to 'clear your mind of everything else'. A reasonable definition of 'focus on a question' is fine. Mostly that instruction is to get you to settle down, calm down, breathe, relax, pay attention to what you're doing. If you stress yourself out about a million procedural details while trying to read, you're going to be too stressed to interpret anything (and getting headaches). So, just relax and 'think' like normal.
6. It really is hard to read for yourself when you're stressed. Just like it's harder to make decisions or be reasonable when you're stressed and not a tarot reader. That's just life. If you journal your readings, it really will reward you in lots of ways. Eventually, you'll gain confidence and experience (that you can 'remember' easily because it's written down), as well as different insights and hindsight and all that good stuff.
Best wishes for this whole situation and your tarot journey and life in general! Relax and try to have fun with the cards.