Ovulation kits - normal? Possible TMI

Currently on cycle day 11 of a regular 26 day cycle. Second month ttc, first time using these opk, Boots own brand. Today's is bottom on pic. Tracking apps say I'm bang in the middle of fertile window - highest percentage chance of getting pregnant should be tomorrow, but if anything the lh surge line on these looks fainter - shouldn't it get progressively darker as I get closer to ovulation? Is there something wrong and am I not going to ovulate? I've never been pregnant before so I'm a bit bewildered by all this and I so want to get it right.

Today's bbt showed quite a big drop and I've had pains in lower abdomen, egg white cm and slight diarrhoea today but I've never tracked my ovulation before so I don't know how it feels or what to look out for.

OH and I have had sex every day of fertile window, am I supposed to save it for when I get a positive on the opk instead? Will do it tonight and tomorrow too, using pre seed. In your experience does the line just switch from faint to dark and I just need to wait a day or do as apps could be off or is something maybe wrong?

Thanks in advance xxx