I am sorry you are dealing with this situation and you are faced with a difficult decision. First, you have a valid argument to present to the course that a portion of your security deposit was unlawfully withheld as you were charged for normal wear and tear,, maintenance and items that were broken by a prior tenant.
A few things you will need to consider. The first, as you have pointed out, you don't have all the evidence that would be helpful to establish your case (move in inspection items, photos) but you do have some photos taken upon move out. What this boils down to is your word against his and whose testimony the judge believes. There is always risk that a judge will not get it right and rule in your favor.
Second, attorney fees are not automatically awarded. Unfortunately lawyers are allowed in small claims in Texas so there is that risk you will have to pay his lawyer fees if you were to lose and the judge grants motion for attorney fees.
Also, it is not easy for a person to make an argument asking for more money and convincing a judge that it is appropriate to award more damages when one had the opportunity to withhold from the security deposit. In other words, it is a little questionable when after you are sued for unlawful withholding of a security deposit to then counter claim and argue you should and could have charged more and didn't. Its a weak argument but again a judge is free to do as they please.
These cases come down to the facts, evidence and testimony. The law opens the door for you as a tenant to sue based on unlawful withholding of the a security deposit. But there is never a way to determine your odds in winning. Do you have a chance, yes, but there is no way to determine your odds going into the court room. You have valid arguments and you do have some evidence to question the veracity of any testimony by the landlord.
One way I look at small claims and weighing the risk and time and hassle of dealing with a lawsuit is whether or not if I win, will I receive more then I will lose if the decision doesn't come down in my favor. In other words, if I am going to win more then I could possible move then I would likely take the risk.
All my best and encouragement. Thank you for allowing me to help you with your questions. I realize this was not the answer you were hoping to receive however I have done my best to provide information which truthfully addresses your question. Please note: If I tell you simply what you wish to hear, this would be unfair to you. I need to be honest with you and sometimes this means providing information that is not optimal. Negative ratings are reserved for experts who are rude or for erroneous information. Please rate me on the quality of my information; do not punish me for my honesty