That is a lot of shakes to start off with.
I have similiar problems with one sometimes.
My solution has been to stop for a day or two then start again
Also I use less psyllium than most. And I drink a big glass of water both before and after but still two half shakes block me up.
I don't think you can gain weight from the shakes except if they are not being eliminated.
If you cannot do colonics or an enema try the dreaded Epsom Salts in warm water. Probably all that 'weight' will come whooshing out.
Also repost your question on Ask Shelley #2. She gives great advice and always answers