Congratulations on your little one. I think three weeks old is a really hard age, you've used up any pre birth supplies of energy you might have had (!), there's a growth spurt, and it's tough.
I was in a very similar position, OP. For me, and I do not judge at all those who chose differently - the decision was to carry on bfeeding and it did - eventually - get easier. But I felt better once I accepted my worth as a mother isn't linked to my ability to resemble a dairy cow and I gave myself permission to stop when I felt that the pain of feeding was not worth 'it' any more. I hope some of the following helps...
I presume you have googled oversupply and your issues, there are different positions to try, techniques for sore nipples (nipple shields can help) I highly recommend the kellymom site or ask specific things here. Also, i didn't believe that after six weeks things would calm down (when I had a shower, it turned the taps on I could drip 50-100ml, I regularly drenched myself in public, etc., so I do empathise with what you say). Honestly, it does, though for me was closer to seven-eight weeks.
Keep an eye on the breast pain and talk to as many bfing 'experts' as you can about it. Do you know of a drop in, bfing cafe, etc.? Turned out my pain wasn't normal, but I would not have found that out if I'd relied on my GP.
and if you don't feel it's for you, it's not the end if the world. However, given that you have an oversupply, if you stop suddenly you risk more complications (mastitis is so not fun) so the advice is to gradually introduce bottles.