Emma Fox, 35, was told she needed an operation to remove the tumour in December 2020 but the procedure was cancelled after a Covid outbreak at the hospital.
There were concerns there was "a very real chance" she "wouldn't make it" if she caught Covid while she was immunocompromised.
But more than two years later, she is still waiting for surgery.
The mum-of-four from Gwynedd was first diagnosed with a brain tumour as a teenager which was successfully treated, but said she always knew it would eventually return.
She was first told she had an Oligodendroglioma - a primary central nervous system tumour - after having a seizure on the bus home from school when she was just 17 and revising for her A Levels.
When she was diagnosed as a teenager she was rushed into emergency surgery.
Emma said: "Because I had been suffering from the age of about three or four with migraines and illnesses I always knew that there was something wrong. I think I was diagnosed and hospital within four days. So it was pretty quick.
She added: "My mum was working abroad as a holiday rep at the time, so she'd had to get an emergency flight home to be there with me in the hospital. I think my mum and dad were more worried than me. Dad cried in the hospital room when I was diagnosed, when they told me there was a tumour in my brain."
The 35-year-old says she did not really process it as the time and "just wanted to get back and do my A Levels."
This time though, with four children aged 14, 13, five and three Emma said: "It's really got to me and I think it is probably because I've got the children to think about, the first time around it was just me. I try not to think about it too much."
She added: "A few years ago, I started to get the migraines again, and the dizziness, I just started to feel how I did the first time I was diagnosed, so I knew there was something going on. And then at my next MRI they confirmed it started to grow. I still haven’t had a date so I am in limbo now.
"My health is getting worse as I'm getting older. I'd rather him [her consultant] do the surgery now. If I've got a fighting chance, I've got more of a reason to get through it now. My kids need me."
The mum-of-four has now had around seven seizures in little over a year and is concerned they could be caused by the tumour growing or spreading.
She has made sure her children are aware of her illness and they all deal with it differently.
She said: "I've got a 14-year-old, he's had to deal with [my] seizures since he was three years old. So I had to teach him how to use my phone and how to open the door to let my dad in. My 13-year-old is autistic and his way of dealing with it is to just shut off. I don't know if it's just his way of coping with it or he just doesn't get it.
"Everyone's got a different coping mechanism. I've got a five-year-old and she knows that mummy falls over and mummy has to lie down and sleep and she's caring most of the time or she will sit and she'll just give me a cuddle, which is nice."And then I've got the three-year-old who is a little whirlwind most of the time, but when I've had a seizure, he sits beside me and he calms down. I don't hide it from them. They know that it will make me sick and maybe I'll have to have an operation so they're going to have to be good for daddy."
Emma is currently on a watch and wait scheme - which involves closely monitoring a patient's condition without giving any treatment until symptoms appear or change. She will have a scan in June to assess whether she still needs surgery and when.
She said that despite her fears, she is "determined" to beat the illness, adding: "I have to get through it for the kids. My older two don't have their biological father in their life. I don't want them to lose me as well."
She has been working to raise awareness of the condition with Brain Tumour Research.
Emma said: "There's very little funding and [it] is the biggest killer of under 40s. And although I've been told that it's highly unlikely my children will inherit it, there is obviously the chance of developing this brain tumour."
She added: "I want to make sure that if they ever have this thing that they might have a found treatment for them."