Nipple shields

Does anyone else use nipple shields? I have a 1 month old and have been using since day 1. I've tried without but she won't latch and just cries until i put bavk on (i have a flat nipple and inverted nipple).

Has anyone had success in not using? They are just so messy and i don't want to use in public.

Also what nipple shields do you use? I have 1 medela but was going to buy a second one but quite expensive and there are lots of ebay options but unsure if good or not.

Thanks!