Hi Renaee,
I am using epi-no too - I know what you mean by how far to put it in, sometimes I have to almost cross my legs to keep it in because it just pops out some days, but I think it's definitely worthwhile, I have only managed to get it up to 8cms though after using it for 3 weeks, but am still trying - I am due any day now so still using it - I think I will be better prepared than if I hadn't used it at all.

I think you are supposed to put it in up to the dip in the balloon and blow it up from there - but have had it in further and that does increase the pressure on the inside, I think both ways is helpful for knowing what that feels like so you don't tense up as much in labour.

Good luck with it and with your birth too