If you were a partner at the prior firm, and you did the designs and were the one to take the pictures you may be at least a partial owner of the copyright anyway.
But the answer to a few questions may make it easier to give you a more solid answer. When you left your prior firm, was there any separation agreement or division of assets? If there was, did it discuss ownership of designs? Are you on any kind of terms with your prior place where they would give you consent if you listed their name as the place where you were when you did the designs? Did anyone else contribute to the designs?
Even though I think you should be on safe footing, it may be best for you to try and work something out with your prior partners.
I think if you get an assignment or consent from the photgrapher (even though it may not be necessary) that you should be okay. Of course, your former partners may sue you just to stir trouble or to drain your resources, but in the end I think a court would likely rule in your favor. Its up to you to balance how much you need the photos versus the likelihood of litigation from the other side.
You've got two issues: (1) can you lawfully claim credit for creating the two interior designs and (2) can you publish photographs of the two interior designs?
1. The answer to the first, under employment law, is generally yes. However, you may still be contractually bound by your partnership agreement (either oral or written) which may prevent you from claiming individual credit for designs created while working for that company. It's likely that the company you previously worked for (as either an independent contractor or employee) has an interest in also claiming credit for the designs. This situation, therefore, may quite easily turn into a dispute. As Oscar notes, you need to ask and answer some fundamental questions about your former relationship with that company before you claim credit. You also need to weigh the benefit of claiming credit with the risk of instigating a dispute should you claim credit. If the benefit is substantial, then you need to invest in some time with an employment lawyer to evaluate your rights and obligations under that former relationship.
Note that "interior designs" are not protectable -- per se -- under any intellectual property law. Your use of the same or very similar designs that you created while working for the company, however, may constitute "unfair competition" under state law.
2. If the company you formerly worked for paid for the photographs, then it is likely that the company owns the copyright in the photographs. A typical photographer's agreement assigns (i.e. conveys or sells) the copyright in the photographs to the one who commissioned them to be taken. If that is the case, then an agreement between you and the photographer is meaningless because the photographer does not have the right to give you permission to re-publish the photographs. Even with an agreement with the photographer, then, you need him to provide you with a copy of his agreement with your former company so you (or more preferable your lawyer) can determine if he has the right to give you permission.