next time try razing with your torch to pop any excess bubbles instead of whipping, whipping to purge quicker tends to trap butane in your oil, while razing brings the bubbles to the top. just keep a safe distance away and gradually get closer, i like to gauge how warm the air is from the tip of the flame with my hand to get a good idea of how far i should be. whipping is okay after the final purge if budder or wax is your desired consistency, but it shouldn't be done during the purge. you should also purge all at once, its much easier to get all the tane out that way, the purge is the most important step IMHO.
i am going to be investing in a pump-n-seal soon, wont break the bank, and from what i've read, pulls a -25hg vacuum quite quickly.