Advice please 😩

I recently realised that my contraceptive implant expired in March. My periods are fairly regular but sometimes they are really messed up and I won't have one for a month or two. Stress usually affects them and recently I've had to hand in my dissertation and had loads of important final year uni exams. My period is now 22 days late (according to this app). I've done multiple pregnancy tests, different brands at different times of the day and they are all negative but I've still not come on my period. Just really unsure of what's going on and I keep getting the kind of discharged like in the picture. Any advice from anyone, should I be worried because my bars expired or is this normal. Just don't know what to do ??