Can't help but be jealous

Indeed.
Some of us might as well be only children based on the siblings we have.

You're jealous of a single mother who returns to the father to 'get pregnant'. I suggest you aim a little higher, and appreciate what you've got. The grass always looks greener, often it's fake grass.

Don’t have another child unless you can afford to support them without the need of benefits.

She said they separate after the positive test, so yes, the sperm donor may be involved, but it doesn't sound like it.

Be fair, she didn't say her friend didn't let the father in the children's lives.

Your friend is a dick, creating children deliberately to avoid work. And she's going to have a much harder life with 3 kids on her own than you will with one. Don't be jealous.

Surely this is a joke?
You'd be happy to find a person to mate with every few years, but not bother allowing them into the child's life.
Another set of kids without a father?
Your friend's attitude is disgusting.

Why don't you just invite friends for sleepovers? My ds often goes to a friend who doesn't have siblings for sleepovers. He's more than happy to leave his brother behind..

The chances you'll give your dd another sibling are high because you're still so young. You just need to put a lot of work into making sure it's with the right person, as that will dictate your family's happiness.

I was in your position though, and had another one to give my dd a sibling, despite at the time not knowing her dad was having a long term affair.
Now divorced and remarried but here's the thing.. my kids have nothing in common with eachother whatsoever and couldn't be less close. There are never any guarantees.

Your friend's situation is nothing to envy. Statistically if she's living in poverty her children will too and have lower attainment in life. The absence of a father who comes in every few years like a bull for breeding is going to cause confusion and probably resentment in the children as they get older and understand what's happening. It all sounds very crass.

Are you dating/looking for a partner?

Children should not sway your decision to have more children, they don't understand what they're saying fully, they just think ooh I'd like a live-in play mate who will do everything I say.

DM was a single mother the majority of the time myself, DB and DSis were growing up.

Given our ages DM spent her 20s, 30s and 40s being a parent before anything else. DB was a complete pain in the arse. All we did was fight. The majority of the time DM didn't work and benefits only go so far. She found it very difficult.

I would be careful what you wish for.

Yes, it's just awful, like a puppy farm.

OP 'longs' for more kids and is irrationally 'jealous' of her friend with more kids than her. This jealousy seems to motivate her longing [to have babies with men who don't care about her or the baby].

Completely separately, OP's 4 yo DD says she wants a sibling. There's a fair chance that wish has been expressed as a result of OP asking, ooh, wouldn't you like a baby sister, or whatever to DD and her saying yes mummy.

On what planet is it a great idea for @Lemon92 to get pregnant with a random bloke and have another baby?

People who want to provide a stable multi-child household for their offspring hold out until those circumstances are achievable.

Unfortunately that shop has sailed. Make the best of existing circumstances. Don't compound the errors.

This x 100000

Poor OP can’t win. Chastised for thinking of what she wants herself, then told to ignore her child’s wishes as kids change their minds every day!

And next week she might want a kitten 🤷‍♀️

Kids wanting siblings or not, should never make part of the adult's decision.

Kids are flaky little fuckers sometimes 😉

Did you miss the bit where OP said her daughter wanted a sibling?

edit - I see you’ve commented on this. It sounds as if your childhood was generally unhappy, possibly for a variety of reasons.

She is not with the girls father but she does go back with him to get pregnant so they all have the same dad and then they seperate when she gets the positive test.

I… is this a common thing? I don’t think there’s anything here to be jealous about lol

Read my second post where I say "I said before it was lonely being the daughter of a single mother. It wouldn't have been less lonely with a sibling. The absence was a loving father - with the emphasis upon 'loving'. Because of course I had a biological father, we all do. And mine was a piece of shit."

And I'm not berating the OP, I'm trying to point out the reality as opposed to the fantasy of her friend who has three kids with a man who takes no responsibility.

Eh? You say how much you hated being the only child of a single mother because it was 'lonely and horrible' then berate the OP for wanting to have another child when the OP literally says, '...and she wants a sibling too, she is always asking for one and she would love the company of a sibling.' She clearly is thinking of her daughter.

i am an only child and very happy to be one too. Your child does not need a sibling to be happy.

I said before it was lonely being the daughter of a single mother. It wouldn't have been less lonely with a sibling. The absence was a loving father - with the emphasis upon 'loving'. Because of course I had a biological father, we all do. And mine was a piece of shit.

I understand why you're jealous OP. I guess you're jealous because you know someone in this situation.

I'm single with one child too.

But there are many advantages to having one child. Put all your love on her and try to concentrate on your own life

So if your DD ended up doing as your DF does in the future just to have siblings and to stay on benefits that’s a life for her you would encourage?