Kinda long explaination.... but could I be pregnant??

I am not on any type of BC (and I don’t always log when me and my husband have sex so don’t pay attention to the hearts really)... When we have sex he always uses pull out method (except ONE day (Jan 31st) he didn’t pull out). I have missed my period as you can see but today, the 23rd and yesterday I have had VERY light spotting. Not even everytime I go to the restroom. It’s just when I wipe and it’s a very pale pink color. I’ve been wearing a pad because I thought my period may be about to come but it still hasn’t came. None of the pink gets on the pad. It’s just when I wipe (and like I said not everytime either).. could this be implantation bleeding maybe? Is it possible I maybe ovulated later than normal? Also I took a dollar store pregnancy test on the 18th and it was negative (just because we had been careless this month).. could I have tested too early? Is it too late for implantation bleeding? We aren’t necessarily TTC but we wouldn’t be upset if it happened at all. Any advice??