any advice please EBF using Nipple shield...

I am EBF but i use a nipple shield i try so hard for him to get my breast without it but he just wont take it...he woukd take a bottle once in a while but his used to me nursing him to sleep..i am planning on stop breastfeeding him at 6 months because i am scared that he might swallow the nipple shield can that even happend??? My baby is 4 1/2 months..any advice please!!!! 😭 i try formula but he throws it up i guess he is not used to it...