hi angel,
firstly, you are not rubbish and he isn't going to hate you. you are doing everything that you think might help him and are pushing yourself to the limit to do it, so please don't be so hard on yourself, even if your final decision is to use formula. you have already given him a fantastic start just getting breastfeeding started.
i might repeat some (or all) of what you've already been told so sorry for that, but i couldn't not reply as i really feel for you and admire your massive committment to getting bf established.
babies do go through growth spurts at various stages and they can last a while but it does pass...eventually, even if it feels like and eternity. breastfeeding can take a good few weeks to get established, even 6, so although it seems like ages you are more than halfway there.
some babies do cry unless latched on/close to mum, and i can think of a few that i know, and at the time their mums found it really hard going. my dd was a constant feeder too, at times and it can be really tiring, she also went from sleeping/content to screaming when she was hungry in a matter of seconds, she still does and if you ask my dh so do i
try spending the day in bed with your baby, and do loads of skin-to-skin as this will encourage your milk supply, help you to notice early feeding cues before he screams (if that's what the screaming is) and allow him to smell your milk and latch on himself, and give yourself a rest and you might sleep too. try using a sling so that you can make a picnic to take back to bed with you. if you think he can be left on your bed long enough for you to have a shower then do it. ask you dp to bring you food etc. keep the phone/tv remote/ a book by you and this is the hardest bit - try to forget about all the other stuff you might be doing.
there is a very very small percentage of women who can't breastfeed very well, but i'm no expert and i think it is, iirc, a supply issue, in that they don't have the right hormone balance to produce any milk, it is rare in humans. it is really unlikely that this is the case with you, if he is putting on weight and producing wet and dirt nappies, and otherwise healthy. there are things that can be done about supply issues and good supprt from bf counsellors/baby cafes/hv/gp/bf helplines/etc can point you in the right direction if needs be. use the support offered around you as much as you think you need it.
breastfeeding does get easier as time goes on - honestly it does and i think that you are doing really well thus far. virtually every women can breastfeed if they want to and even the above mentioned case, i do know of someone who still managed to bf a tiny bit even though they were probably nourished by formula. it does have a bit to do with mindset and sometimes you do have to accept that in the early days (and this is still early days) there will be days that you can't get out of your pj's for bf, but it is quite normal albeit a bit frustrating/stressful/etc.
lastly, and i'll stop rambling after this don't be so hard on yourself, you have done so well already and whatever you decide re feeding will be ok. believe in yourself you are not failing him as a mother. it will get better and you will enjoy him. your body goes through a shedload when you have a baby and you've got all those hormones tearing around and you will be exhausted: the first weeks are really hard going.
sorry for loooooooong waffle
take care x