You are wrong.
India was formally offered the UN permanent seat twice by the US.
Before August 1950 an offer was made to assist India in assuming a permanent seat at the UN Security Council.
The proof is in the letter from the Indian Ambassador to the US , Mrs. Vijaya Lakshmi Pandit, Nehru’s sister and is part of Indian official record held at the Nehru Memorial Museum and Library (NMML), New Delhi.
The letter says,
"One matter that is being cooked up in the State Department should be known to you.
This is the unseating of China as a Permanent Member in the Security Council and of India being put in her place. I have just seen Reuter’s report of your answer to the same question. Last week I had interviews with [John Foster] Dulles and [Philip] Jessup, reports of which I have sent to Bajpai. Both brought up this question and
Dulles seemed particularly anxious that a move in this direction should be started. Last night I heard from Marquis Childs, an influential columnist of Washington, that
Dulles has asked him on behalf of the State Department to build up public opinion along these lines. I told him our attitude and advised him to go slow in the matter
as it would not be received with any warmth in India. "
"Dulles" mentioned here is
John Foster Dulle who later became Secretary of State in 1953.
Nehru's response was also quite startling, THIS is what he wrote back,
"In your letter you mention that the State Department is trying to unseat China as a Permanent Member of the Security Council and to put India in her place.
So far as we are concerned, we are not going to countenance it. That would be bad from every point of view.
It would be a clear affront to China and it would mean some kind of a break between us and China. I suppose the state department would not like that,
but we have no intention of following that course.
We shall go on pressing for China’s admission in the UN and the Security Council. I suppose that a crisis will come during the next sessions of the General Assembly of the UN on this issue. The people’s government of China is sending a full delegation there."
This move by the US was after the June 1950 Korean War which china supported and India opposed.
Also to be noted here is the China's membership was still pending since it was the ROC (Taiwan) who was the founding member and not PRC (china).
PRC membership was kept in limbo right till 1971.
Also to be noted was the fact that USSR was not attending the UN till August 1950 (it had Boycotted the UN) and till then US called the shots in the UN.
USSR made the offer of adding India as the
Sixth UN Permanent member in 1954-55. This is part of USSR official record. This was after USSR serious differences with china. India till then had full support of the US and with USSR warming up this could have fructified if it wasn't for the paranoia of Nehru.
Nehru's official response is also part of recorded history,
Nehru: “Perhaps Bulganin knows that some people in USA have suggested that India should replace China in the Security Council. This is to create trouble between us and China. We are, of course,
wholly opposed to it …”
This offer was made in the context of the Charter envisaged a General Conference before the tenth annual session of the General Assembly. If this was not done, article 109 mandated ‘the proposal to call such a Conference shall be placed on the agenda of the session of the General Assembly’. This deadline was fast approaching in 1956. USSR wanted to push India before this time frame.
If India had negotiated a understanding with both the US and USSR by 1955-56, we would have been a permanent member. But for the obstinate Nehru.
In fact India continued to support china's seat as permanent member EVEN AFTER CHINA ATTACKED INDIA in 1962.
This too is part of our official record and is documented in various world media. In fact this question was directly put the Indian govt. by the US media when we went to attend the UN post India china war and our reply was that it was two separate issue and Indian stand was based on its "moral conviction".
In fact you might want to read up on Dr. Ambedkar's view on Nehru and his foreign policy w.r.t China. He was blunt and contemptuous of Nehru's cowardice and fence sitting. Hence it has been white washed from history.