When well-meaning friends urged her to have a few one-night stands, the brunette replied with a flat 'no' because, she says: "I didn't want that to be what I told my child about his daddy."
Doreen explains: "I wanted to have a baby by the time I was 35 and that's what I did. I was talking to someone one day saying I hadn't met someone, and she said to me, 'Sure, do it yourself'. I don't even remember who it was, just the comment.
"So my mam said, 'Sure, make the appointment' and I did and then next thing I knew I was doing fertility treatment. I went in for bloods, I was down €500 and then I was in, I had a treatment plan.
"I just did it because what's the point in talking about it in 10 years."
Doreen, who comes from Termonfeckin in Co Louth tells: "I'm a chef in Baltray Golf Club; I am there 20 years, and I loved my job, but I wanted a baby.
"I did three rounds of IUI against the advice of the doctors, and it didn't work and then they told me to do IVF. I was so upset that I'd wasted all that money, but I just came home, and I said to mam, 'I am going to go for it, one more time'."
Determined to give her all, Doreen had fertility treatment in Sims IVF in Dublin. She started her fertility treatment in December 2017 and was pregnant in January 2019.
"The doctor said that transfer was 'beautiful'. I always remember that. I knew it had worked because three days later I couldn't look at anyone, I was in a dark room, and I had a terrible headache. I'd never felt so bad," she says.
"Exactly a week later I had to do the blood test and my mother was like, 'Don't do a home test, you are to wait until the blood test'.
"Of course, I did about 20 tests, in the morning and the evening - I'd say there is 10 positive tests above in that bag."
At the time, Doreen felt lonely on her IVF journey, but says even in a few short years the solo mum has a voice on social media and the national press.
"I did find a group halfway through, but it was secretive," she continues. "Now there are so many doing it alone, and Noah is not even two yet. It just helps to know other women are doing it.
"My pregnancy was grand and then at seven weeks I was told I was carrying twins. I was like, 'Oh my god, my mother is going to have a mental breakdown'. I got my head around it and then, at 12 weeks, I lost one. But I have my little man - I have Noah.
"I was seven-and-a-half months pregnant when I finished work and I'd just done a wedding and it was a really hot day and I sat down and I just said, 'I'm done'. My boss was like, 'What?' and then he said, 'Well, I am actually delighted for you'."
The loving mum found the process of choosing a donor for baby Noah difficult because the clinic shows you pictures of the donors as babies - not grown men.
She laughs: "You can go on to these websites and they are all picture of babies, and all babies are so cute, like how could I choose one? So I went to the Sims IVF counsellor and she asked me what I was struggling with.
"When I told her, she told me that years ago you used to choose it from a sheet - so I chose red hair, blue eyes, sallow skin, like me, and medium height. She rang the lab and they said we have someone that matches all those.
"Recently I rang the clinic and asked to see his donor's profile picture, and Noah is very like him, but then people who don't know say he is the spit of me, so he is a nice mix. Noah can contact him if he wants when he is older."
She adds: "When I look back, I think how did I do all this on my own? But you know I couldn't be happier.
"The last four nights he has woken at 4.22am like clockwork and he is sitting up in the cot and he is dancing around."
As for cuddles, the doting mum jokes: "I don't get too many, he is too lively, but we are delighted with him - he's the best.
"I haven't had any help because of the pandemic - otherwise it would have been so much easier - but that's just the way it is. He is my little ray of sunshine and he makes the hard days better.
"It really was the best decision I ever made. I remember I was so excited and nervous but I am so glad I just took the plunge."
The Ticking Clock is a six-part series, starting today, which celebrates the miracle of fertility medicine with real-life stories, video content and expert advice each week - online and in print. Watch Doreen tell her true story on sundayworld.com and sims.ie in her own words, with special guest Noah Cullen