A weak Iman is a disease of the heart. And like all diseases this too has its symptoms/signs. Those signs are more apparent, and perhaps we can list these and perform a self-assessment of our Iman.

There are 20 signs of weak iman (faith) dan hopefully we can increase our Iman. Here there are the list:

1. Committing sins and not feeling any guilt.

2. Having a hard heart and no desire to read the Quran.

3. Feeling too lazy to do good deeds, e.g. being late for salat

4. Neglecting the Sunnah.

5. Having mood swings, for instance being upset about petty things and bothered and irritated most of the time.

6. Not feeling anything when hearing verses from the Quran, for example when Allah warns us of punishments and His promise of glad tidings.

7. Finding difficulty in remembering Allah and making dhikr.

8. Not feeling bad when things are done against the Shariah.

9. Desiring status and wealth.

10. Being mean and miserly, i.e. not wanting to part with wealth.

11. Ordering others to do good deeds when not practising them ourselves.

12. Feeling pleased when things are not progressing for others.

13. Being concerned with whether something is haram or halal only; and not avoiding makroo (not recommended) things.

14. Making fun of people who do simple good deeds, like cleaning the mosque.
    
15. Not feeling concerned about the situation of Muslims.

16. Not feeling the responsibility to do something to promote Islam.
 
17. Liking to argue just for the sake of arguing without any proof.

18. Being unable to deal with calamities, for instance crying and yelling in funerals.

19. Becoming engrossed and very involved with dunya, worldly things, i.e. feeling bad only when losing something in terms of material wealth.

20. Becoming engrossed and obsessive about ourselves.  

Reference: Islamway.com