Hiii! Linguistics minor and massive stutterer here. So the issue with P and vowel-initial words are actually because both begins with a stop. With words beginning with vowels in English, they actually begin with a silent glottal stop. Try using an “h” sound sliding into words starting with vowels. As for the words beginning with p, try using a voiceless bilabial fricative instead. Make an “f” sound, but then get your lower lip out from under your teeth. You should have your lips functionally closed-ish, but just let the air flow out through the little opening that blows air out between your lips. It’s close enough that English speakers won’t really notice. If you need help producing the sound, there are production examples on linguistics youtube. Look up “voiceless bilabial fricative”