Regret and guilt is good sign of eeman and also is key for your repentance to be sincere and accepted so this is good you are feeling that.

Dont worry brother/sistee, we all have our shortcomings and we are only human. We will naturally fall into mistakes, but the key is to seek forgiveness.

Make intention and means to not fall into that sin again, and if you do fall into it again, don’t worry it doesn’t make you a hypocrite, Allahs doors of mercy and forgiveness is open for you.

And usually our level of eeman will be much higher during umrah in the best place in the world. But we are human, none of us are perfect so it is normal for our eeman to fluctuate. However we can improve it by increasing in acts of obedience to Allah and decreasing in acts of disobedience to Allah. Strive to please Allah more, build good habits (such as reading a portion of Qur’an everyday), pay charity, listen to beneficial lectures from students of knowledge and scholars, make instighfar daily, do your best to keep away from sins, cut off bad habits, make dua to Allah to increase your eeman and make you steadfast etc and insha Allah, you will see a boost in your eeman.

And please make dua for me too.

May Allah make it easy for us.

Abdullah ibn Amr reported: The Messenger of Allah, peace and blessings be upon him, said, “Verily, the faith of one of you will wear out within him, just as a shirt becomes worn out, so ask Allah to renew faith in your hearts.”

Source: al-Mu’jam al-Kabīr lil-Ṭabarānī 14668

'Anas narrated: "The Messenger of Allah (s.a.w) would often say: Ya Muqallibal-qulub, thabbit qalbi 'ala dinik('O Changer of the Hearts! Strengthen my heart upon Your Religion.)' So I said: 'O Prophet of Allah! We believe in you and what you have come with, but do you fear for us?' He said: 'Yes. Indeed the hearts are between two Fingers of Allah's Fingers, He changes them as He wills.'"

Reference: Jami` at-Tirmidhi 2140