You really need experienced RL help here, OP. The problem with breastfeeding support is that you often really have to fight your own corner for it. It's not how it should be :( but it is unfortunately the case.
If you are happy to stop now, then do it, don't feel guilty, you have done your baby a world of good by feeding up until this age. There's a great poster which shows the benefits of breastfeeding up to different ages:
First feed
Helps to stabilise baby?s blood sugars and
protect baby?s gut
A great opportunity for the first skin to skin
cuddle
1 day
The antibodies in your colostrum provide
natural immunity from infection
Helps womb to contract towards normal size
2-3 days
Sticky black meconium is cleared more readily
from baby?s bowel
Instant relief for hot, swollen breasts when
your milk comes in
1 week
Transition to world outside womb is eased
Frequent feeds means time to sit or lie down
and for you and your baby to get to know each
other
2 weeks
Food and drink always ready at the right
temperature, adapting to baby?s needs
Hormones help you get back to sleep after
night feeds
4 weeks
For premature babies lower risk factors for
heart disease in later life
Saves time sterilising and making up bottles
6 weeks
Half the risk of chest infections now and up to
seven years old
^ That is all of the good that you have done for your baby so far, and if you want to stop, that is an absolutely valid decision and should be respected. If this is what you have decided please skip past the rest of my post.
If you really, really want to carry on, it will be worth fighting for.
Tongue tie can be (and is frequently) missed. I'm only seeing a couple of signs in your post but it would be worth looking into - you need someone who is really experienced with it. You might need to hassle the various BF helplines or look at www.milkmatters.org.uk - they have experts who will come out to see you personally. You're probably not going to find a tongue tie expert in a breastfeeding support group, although it's possible.
Sounds like you may have a problem in the boob which is sore - does it feel sort of lumpy or is there a red patch which is sore and hot? That could be a blocked duct which can lead to mastitis if it does not get cleared. If it's sort of shooting pains deep within the breast then it's more likely to be thrush. If you think it's mastitis or thrush then you need to seek medical advice ASAP. If it's that he's chewed the nipple then that will be self evident. Have you got any Lansinoh? You could also look into nipple shields. They aren't great long term, but as a tool to help make feeding more bearable until it improves they are invaluable.
Being alert after feeds is really really good. That is one of the signs he's getting lots of lovely food and drink from you. Are you sure he is not satisfied, ie, is he rooting again, or is he just unsettled? Most babies will accept a bottle and then look magically settled afterwards whether they were hungry or not - have you tried winding him, walking around with him? If he's crying but doesn't want to go back on the boob it might be that he just wants to suck, you could try your little finger, or a dummy.
30ml is quite a normal amount to express in one go and doesn't mean your supply is low or that's all you have "left". Supply doesn't work like this and doesn't need time to refill, so try not to worry about this. A baby is far more efficient than a pump.
You could try a biological nurturing position as this is different to other positions and lets the baby find their own way, usually leading to a better latch. Google this for more detailed instructions or a video, however, all it is is you lying semi-reclined and putting the baby skin to skin on your chest allowing them to "crawl" up to the breast and latch on. They can do this from a few minutes old, so he isn't too young. It's quite amazing to see - don't be tempted to help him.
Good luck!