Yeah bro, so the uhm sound before the actual m might pass for you just thinking/gathering your thoughts and as for S, "uh" works as a good filler sound too, like "I'm not too fond of-uh-spiders". Might work, just sharing what my doc told me, these sounds were blockers for me too. Man, I used to write what my parents sent me to get on a piece of paper so that I wouldn't have to say it to the shopkeeper, this is some 10 years back in my home country.