Yes I did, though I wouldn't say it was through choice exactly.
It took me over 9 weeks to establish BF with DS, my first child. Had I known it would take that long, I wouldn't have bothered tbh, because I wasn't as well-informed about the powers of breastmilk as I am now. I had good days where,just as I was about to give up and buy formula, we had a couple of days when I thought I'd cracked it, and that kept me going. I bf for about six months before going back to work (again, didn't realise the huge benefits of feeding beyond 6 months and would have done things differently if I had done).
The factors which kept me going were a) sheer blissful ignorance of the fact that it could take so long to establish bf and b) a wonderfully supportive, well informed HV who was also a fully trained BF counsellor so didn't talk a load of shit about BF like most of them.
With dd, I had 2 weeks of hell with no good day. I'd moved house, was now a lone parent, and had a toddler to look after. I also very, very importantly, didn't have a BF counsellor as a HV, I had a bog standard one who as usual couldn't cope with bf and felt insecure and worried about it. The combination of having an older child to look after and no support, were the main factors. Also of course, the lack of knowledge of the real differences between formula and breast milk. I knew "breast is best" but it was only as a result of a thread on Mumsnet a while ago that I realised I'd also subliminally imbibed the message "but formula is near as dammit". Had I not believed that, I think I would have sought more support and tried for longer.