Nipple shield use

For how many of u has the nipple shield been a blessing for breastfeeding. That is the only reason u could breastfeed. I have small nipples n I have been using the silicone nipple shield till now (baby is 6weeks old). Can't breastfeed without it. Is there anyone who has continued using them? How do u clean them after use? Do u sterilise them each time and how?