When I was in hospital after giving birth to my boy, a midwife told my husband: "Two weeks old is when most mums find Breastfeeding the hardest. 2 weeks in is when many mothers decide to quit." I forgot the midwife had said this, but at the 2 week mark I had a very teary day and was frustrated at how painful and demanding breastfeeding was, my husband reminded me of this, and encouraged me to hang in there, because it will get better.
And it has got better, even just 2 weeks later.
Definitely see a lactation consultant, they can advise you on latching, also ask them to check baby for a tongue tie. My 4 week old had his anterior tongue tie cut this week and there has been a massive improvement to his latch and our breastfeeding relationship because my toes aren't curling every time he eats now.
I'm also using nipple shields to help heal my damaged nipples.
I've been advised by midwives and nurses that you can't overfeed an exclusively breastfed baby. The baby knows what he needs, and the body responds with the right type of milk ie on hot days you will make more thirst satisfying milk, at night, your milk has higher sleep-inducing components.
I've found this website to be an amazing and informative resource for all my questions about breastfeeding. www.breastfeeding.asn.au/bf-categories
As for cluster feeding, that's also completely normal. Babies do it whenever they're going through a growth spurt or developmental leap (ever heard of wonder weeks?), whenever they are in pain, or when they just need some extra food or comfort.
My little one cluster fed on day 1-5, then again at 2 weeks, and now at 4 weeks he cluster feeds most evenings from 5pm-9pm, feeding every 30-60 minutes, before falling asleep for a long sleep stretch of at least 5 hours. Every baby is different, but cluster feeding in the evenings is quite common, there's nothing wrong with your milk or your supply. And I'm all for cluster feeding in the evening if it means we all get a bit more sleep!