Custom QGraphicsItem drawn in position different from the one given

[LightJeep]

Hello everyone, I'm working in a program to create graphs and I'm currently working in the Node class which inherits from QGraphicsItem. I am placing these Nodes in a QGraphicsScene and if I set the position of the Node in QPoint(100, 10) the item gets drawn in a different position, what's weird is that if I set a position farther from the origin, the bigger is the offset of where it's drawn.

I have set the position of the first Node at QPoint(100,10) and the second Node is at QPoint(200,20), to visualize the offset caused by the problem I have drawn circles at the exact same position of each Node where they should be drawn.
example.jpg

Heres the code:

MainWindow class

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    scene = new QGraphicsScene(this);
    ui->graphicsView->setScene(scene);
 
    Graph* graph = new Graph();
    Node* A = new Node();
    Node* B = new Node();
    graph->add(100,10, A);
    graph->add(200,20, B);
    graph->link(A, B);
    scene->addItem(graph);
 
    //TESTING COORDINATES
    scene->addEllipse(100,10,1,1,QPen(Qt::red, 30));
    scene->addEllipse(200,20,1,1,QPen(Qt::blue, 30));
}

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    scene = new QGraphicsScene(this);
    ui->graphicsView->setScene(scene);

    Graph* graph = new Graph();
    Node* A = new Node();
    Node* B = new Node();
    graph->add(100,10, A);
    graph->add(200,20, B);
    graph->link(A, B);
    scene->addItem(graph);

    //TESTING COORDINATES
    scene->addEllipse(100,10,1,1,QPen(Qt::red, 30));
    scene->addEllipse(200,20,1,1,QPen(Qt::blue, 30));
}

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Graph class, inherits from QGraphicsItemGroup
With this class I am putting all the nodes in a group hoping that it will benefit me later if I have the need to move the whole graph once created.

Graph::Graph()
{
 
}
 
void Graph::add(qreal x, qreal y, Node *node)
{
    addToGroup(node);
    nodes.push_back(node);
    node->setPos(x,y);
}
 
void Graph::link(Node* A, Node* B)
{
    A->linkNode(B);
    Edge* edge = new Edge(A,B);
    addToGroup(edge);
    edges.push_back(edge);
}

Graph::Graph()
{

}

void Graph::add(qreal x, qreal y, Node *node)
{
    addToGroup(node);
    nodes.push_back(node);
    node->setPos(x,y);
}

void Graph::link(Node* A, Node* B)
{
    A->linkNode(B);
    Edge* edge = new Edge(A,B);
    addToGroup(edge);
    edges.push_back(edge);
}

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Node class, inherits from QGraphicsItem

Node::Node()
{
    setRadius(15.0);
}
 
QRectF Node::boundingRect() const
{
    return rect;
}
 
void Node::paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget)
{
    painter->setPen(QPen(Qt::black, 4));
    painter->setBrush(Qt::red);
    painter->drawEllipse(pos(), rect.width(), rect.height());
}
 
void Node::setRadius(qreal radius)
{
    rect.setSize(QSizeF(2.0*radius, 2.0*radius));
}
 
void Node::linkNode(Node* node)
{
    this->adjacency_list.push_back(node);
    node->getAdjacencyList()->push_back(this);
}
 
QList<Node*>* Node::getAdjacencyList()
{
    return &adjacency_list;
}

Node::Node()
{
    setRadius(15.0);
}

QRectF Node::boundingRect() const
{
    return rect;
}

void Node::paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget)
{
    painter->setPen(QPen(Qt::black, 4));
    painter->setBrush(Qt::red);
    painter->drawEllipse(pos(), rect.width(), rect.height());
}

void Node::setRadius(qreal radius)
{
    rect.setSize(QSizeF(2.0*radius, 2.0*radius));
}

void Node::linkNode(Node* node)
{
    this->adjacency_list.push_back(node);
    node->getAdjacencyList()->push_back(this);
}

QList<Node*>* Node::getAdjacencyList()
{
    return &adjacency_list;
}

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What could be causing the Nodes to be drawn at different positions from the ones given in the QGraphicsScene, what am I doing wrong? Thanks for the help in advance!