Is this invalid test, a positive or ink smudge??

[TheCosyPinkSnake]

We had unprotected sex on 28th and 29th November. I was expecting my periods on 8th December and did test on 9th December. It was negative. Still no periods. It's 11 December now and attached is what the result says. I don't know what is this. There is a small dot near control line. I am so much worried.

Invalid test. Take another one.

Just to mention one thing here. I saw very minor spotting on 9th december and 10th december as well.

Depending on your cycle length it seems quite likely the 28th and 29th of November were after ovulation and so outside the week (ish) where you could fall pregnant. But, if you ovulated late for whatever reason this month then you could be pregnant and you might not get a positive test for another few days. If a test is still coming up negative today, I’d test again on the 13th (2weeks after the unprotected sex) and if that’s negative but your period still doesn’t turn up a week later, test again on the 20th. By three weeks after unprotected sex, whatever weird thing your cycle is doing this month, a pregnancy test should give you a clear and accurate result.

I retested and this is what I got. Is it still too early as you said I should be testing it on 13th? Let me share my cycle details as well . I am sharing starting dates of each month just to make it clear.

4 august
5 september
6 october
8 november
and now spotting on 9th december. (don't know if it's early period blood or what)

So those cycle lengths are 31 days, 31 days and 33 days and you were expecting your period on the 9th of December after 31 days. That test looks negative to me. But your period is late. It could well just be that your cycle is a bit off this month. If we assume your cycle is doing bizarre things this month then 2 weeks after the unprotected sex when your period is overdue is a good time to test because there is usually about 14 days between ovulation and the date your period should turn up. So if you weirdly ovulated on the 28th or 29th then testing two weeks later should give you a pretty accurate answer. But if your cycle is way off this month and you didn’t ovulate until later than that, then testing three weeks after unprotected sex should give you a fairly definitive answer. Sperm can live in the female body for about 5 days. So if we stretch that to a week to be sure and then you test two weeks after that, then even if you ovulated crazy late a pregnancy test should be accurate.
You very occasionally get women who get negative tests even when they are very definitely pregnant (no idea why but it’s something that women post about on Mumsnet from time to time) so if your period still doesn’t arrive shortly after those three weeks and a negative test you might decide to go and see your gp to check what’s going on - probably nothing much, sometimes periods go awol when we’re stressed or losing weight for example.

It's 12th December. It's negative again. I am thinking to go for blood test tomorrow. Will that be 100% accurate? Or if blood says negative I still need to wait for few more days to make it sure?

https://www.nhs.uk/pregnancy/trying-for-a-baby/doing-a-pregnancy-test/

Blood tests measure the same hormone as at home urine pregnancy tests - just a little more accurately.
NHS says the same thing about needing to wait 21 days after unprotected sex if you’re not sure when your period is due (meaning not sure when you would have ovulated). I think you’ll still have to wait til the 20th for a definitive answer OP.