uncontrollable crying while nursing

Li
This is mostly venting because he has plenty of wet diapers/dirty and is gaining weight so I guess he is getting enough. 
  But for the past two days my 7 week old baby has just screamed while at the breast while trying to eat. It takes 20 mins for me to maybe have him latched and eating for 5 minutes or less 
It's only the last feed before bed and his first morning feed that he will nurse for 15-20 minutes like I'm use too. And every feed after that it's like the boob is trying to kill him,he just cries and screams. during his 2 night feeds he eats for 3-5 minutes then falls asleep and I do everything I can to wake him up, tickling changing bum, taking clothes off etc
 I'm scarrrd he's not getting enough but he has plenty of wet/dirty diapers so I know he is but still I'm worried 
 I've tired holding him every which way, I'burp him and try again and he still screams. For 20 minutes I'll wrestle him to latch and he'll eat for a total of 3-5 minutes then fall asleep. And not show hunger signs for 2.5-3 hrs later and it starts all over again, I ve tried waiting to make sure he's really hungry and feeding him as soon as I see a hungry cue and neither have helped
 I thought nursing was suppose to be calming for baby but it just seems to be hurting him the way he cries while eating. It's so stressful because I feel like he should be eating for longer and not screaming the whole time. 
I do have an over active let down and try my best to work around it but could thy be reason he screams? Is crying while eating normal at this age? Is all this crying/screaming  to stressful on him? Is it something I could be eating and he doesn't like my milk?Even though he has over 7 wet diapers and 3 big poops a day could he still be not getting enough like is nursing for less than 5 mins every 3ish hours enough for him? 
Added the picture to make me feel better