He forgot one circuit of tawaaf and he did it after completing saa’i

Tawaaf for ‘umrah or Hajj must be seven circuits, and it is
not acceptable to do less than that, because Allaah has enjoined tawaaf and
said: “and circumambulate the Ancient House (the Ka‘bah at Makkah)”
[al-Hajj 22:29]. 

And the Prophet (peace and blessings of Allaah be upon
him) explained that by his actions, and he did seven circuits and said:
“Learn from me your rituals of Hajj.” Narrated by Muslim (2286). 

Al-Nawawi (may Allaah have mercy on him) said: The condition
of tawaaf is that it must be seven circuits, each one starting and ending at
the Black Stone. If one step of the seven is omitted, then his tawaaf does
not count, whether he stays in Makkah or has departed and returned to his
homeland, and it cannot be rectified by offering a sacrifice or anything
else. End quote from al-Majmoo’ (8/21). 

Secondly: 

Doing the seven circuits without interruption is a condition
of tawaaf being valid according to the Maalikis and Hanbalis; if there is a
lengthy interruption between any two circuits, then tawaaf must be
repeated. 

It says in Kashshaaf al-Qinaa’ (2/483): If tawaaf is
interrupted by a lengthy interval or because they forgot or because of some
excuse, then it is not acceptable, because the Prophet (peace and
blessings of Allaah be upon him) did the circuits of tawaaf one after
another, and he said: “Learn from me your rituals of Hajj.” End quote. 

See also: Mawaahib al-Jaleel (3/75) and
al-Mawsoo’ah al-Fiqhiyyah (29/132). 

It says in Fataawa al-Lajnah al-Daa’imah (11/253): If
the pilgrim does tawaaf al-ifaadah and forgets one of the circuits, and
there is a long interval, then he must repeat tawaaf. If the interruption is
brief, then he may do the circuit that he forgot. End quote. 

Thirdly: 

The majority of fuqaha’ (including the four imams) are of the
view that it is not permissible to do saa’i before tawaaf, and that if a
person does saa’i before tawaaf, it is not acceptable. 

Ibn Qudaamah (may Allaah have mercy on him) said in
al-Mughni (3/194): Saa’i comes after tawaaf, and it is not valid unless
it is preceded by tawaaf. If saa’i is done first, it is not valid. This is
the view of Maalik, al-Shaafa’i and as-haab al-ra’i. End quote.  

Based on that, your doing the seventh circuit of tawaaf after
finishing saa’i does not count, because of the lengthy interruption between
it and the other circuits. 

Similarly your saa’i does not count because it was done
before completing tawaaf. 

Based on this, you are still in ihraam right now, and you
have to avoid all the things that are forbidden in ihraam, and go back to
Makkah to do tawaaf and saa’i, then shave your head or cut your hair, and
thus your ‘umrah will be over. 

Shaykh Ibn ‘Uthaymeen (may Allaah have mercy on him) was
asked about a woman who did tawaaf al-ifaadah with six circuits, thinking
that it was seven. After doing saa’i and cutting her hair, she did one more
circuit. Is that permissible? 

He replied: If she was certain that it was six circuits, then
doing the seventh circuit after a lengthy interruption is of no benefit. Now
she has to repeat tawaaf from the beginning, with seven circuits. But if she
was merely uncertain after finishing tawaaf, and she thought that she had
not completed it, then she should not pay any attention to this. End quote
from Majmoo’ Fataawa al-Shaykh Ibn ‘Uthaymeen (22/293). 

And Allaah knows best.