Barb has given you some great advice. I fed my DD for 10 months full time, starting from birth, with a shield and she was a quicker feeder than some of my friends who didn't use shields so I don't think using a shield would change the length of time. I used the medela brand shields and found them great. Best of luck and well done for perserving and giving it a go. Don't forget if you need any help, day or night, the women on the ABA helpline are absolutely brilliant. Their number is 1800 686 2 686 (1800 mum 2 mum). Good luck.