running out of pages in our passport (uk passport)

heya ! me and my fiance have been doing our once in a lifetime travel of south east asia. we have run into a problem where we have maybe 5~4 pages left blank in our passports and 7 countries left (malaysia, singapore, indonesia, china, south korea, philippines and japan).

we cannot renew our passports in an embassy and going home to renew them would cost enough to end our trip.

we didn’t anticipate 2 page visas in some of the countries we have been through, we came out with what we thought was plenty of pages and have been caught out.

we have space on some pages for just stamps - however if they are full page visas we are worried we will run out of space !

any advice or knowledge on stamps/ pages and how tricky we will find it would be great !!