And the reaction was explosive with 20,000 people sharing the image within 24 hours, the Daily Mail reports.
Travelling on a C2C train service in Essex at the time, she said she asked if she could sit down where men's suitcases were but she was ignored.
Writing online, she said: "Having to stand on a train while breastfeeding my baby thanks to the lovely bunch of charmers giving more priority to their suitcases and rolling joints. It stinks.
"Plus the cyclist with a fancy bike that keeps rolling into me, sat in the disabled seat.
"Please share cos I'd love it if their mothers, girlfriends and wives get to see how they behave."
Asked by a friend if the people possibly didn't realise she was breastfeeding, Bryony, who says she is an advocate of natural parenting, claimed they "1000 per cent knew".
She responded to a friend: "The fact I stood by them for a few minutes and then asked if I could please sit where the suitcase was and yet they ignored me completely.
"The suitcase was being used as a surface to roll their joints. Then they stared at me for ages - disgusting excuses for human beings."
Sensationally Ms Esther revealed she was even messaged after putting the post online by people saying her baby looked "too old" to be breastfed.
Others have written to her to say she is an "exhibitionist" or she should "get a car".
With now more than 35,000 shares and comments, it has prompted a fierce debate.
One woman wrote: "This is bloody terrible hun, poor you. You must have super strong arms feeding and standing up. Some men don't know how to show respect.
"I have always given my seat up on public transport to the elderly and expecting mothers that I've seen struggling."
Others weren't as sympathetic.
A man wrote: "Women say they want equality and want to be treated the same as men but then get upset when something like this happens. Also her child is a bit too old to be breastfed, surely solids will suffice?"
This is the second incident of a mother hitting out at "rude" comments on the subject of breastfeeding.
Earlier this month a parent defended herself after a stranger ordered her to "put her ****** **** away" after she posted pictures of herself breastfeeding online.
Health officials say breastfeeding is good for both mothers and babies, reducing the risk of heart disease and stroke in parents by up to 10 per cent.