Perfectly happy to be told AIBU if I am, 36 weeks pregnant so my grip on reality and reasonableness is possibly a little loose 
Had a run in with the water babies brigade at my local pool yesterday. Had a lovely swim with DD (22 months) and played with another mum and toddler boy who we had never met before. DD and the wee boy played beautifully. Stayed in a bit longer as they were having so much fun then we all got out and grabbed a family cubicle each (there are 3)
I strapped DD into the toddler chair and was getting changed when someone bangs on the door. Ignored it and 2 mins later it happens again. Open door to find 2 irritate mothers standing holding small babies (3/4 months) saying they need to use the changing table (also in cubicle) to change their babies as lesson was due to start in 15 mins and more mums would be there soon. I explained I needed to change DD on the table & finish getting myself changed, said would be as quick as possible and shut door.
So carried on to audible mutterings from outside cubicles. In the
end just took my time and changed at usual speed (15 mins for both of us) and left as quickly as possible, was pretty quick as mum and toddler boy were still changing in next cubicle. Came out to find lesson had started & 3 mums were still stood there which surprised me, there are 2 tables in the toilets!
Petty I know but curious AIBU? Should I have given them the cubicle? I figured being 36 weeks pregnant and toddler in tow gave me just as much 'right' to use family cubicles or should they be for smaller babies?