Trigger?

hi-i need help--i've been on my journey since late jan and have made progress slowly and in fits and starts but i need help now--i've been blogging all the while(ed's journey)--anyway i have the mgx, the helix and the progasm and just got the advanced set of the peridise--i'm to the point where i can relax to get something going, then grab it with slight pc, anal or rectal contractions, holding it until it builds and gets stronger and better, but it never takes me over the edge--it is nice and builds and then subsides and then i relax to start again after waiting a good amount of time to see whether it will come back on its own--i do this over and over again, and although they are a lot of fun and give me pleasure, i haven't yet been able to get them to the self sustaining level where they will repeat by themselves--- i have the idea that you will say keep it up and you will get there but i wondered if there was something else i could do to get over the brink??