Hi Catia....Tessa is a lovely looking girl and I can see a lot of TM in her, not sure about what the other part it and kind of have doubts about a Rottie but if the breeder says her mom is a Rott then I guess she would know what she is talking about but for sure the TM side of her is strong.
So glad to see you are socializing your girl, but have to butt in and say dont be suprised if one day she doesnt take so well to the dog park any more. You very well may come across a dog or two she takes issue with, for no apparent reason in our eyes, but for very good reason in hers and TM's are near enough impossible to read body language with. The best thing to watch out for is a high head, stiff and serious walk and a medium set out tail, neither up nor down but straight out. When they are in the stance I would say watch it. Also the turning of the head and ignoring of outside affections, this is a universal signal with most dogs but one to pay heed to with a TM.
I am sure you have realized how stubborn and frustrating they can be as well! LOL. This breed is a challenge and a half to train, esp with off lead recall. I am pretty lucky with my girl as she is about 95% which took a hell of a lot of hard word, and I mean HARD WORK, but still its 95% at best. If she gets it in to her head that there is a threat she will not come back for love nor money nor ice cubes.
I have been MIA from this forum for a while lately due to having family visiting but just shout if you have any questions that Ruth hasnt already answered....she is better than I am. LOL.
I will leave you with this little.....this weekend my hubby and I took my family to a lovely place here in the UK called Lincoln, we also took our dogs, one of which is Mooshi our TM. Whilst we were sitting waiting for our family to join us from their tour of a local cathedral a strange man started to walk towards us. He was an older chap, probably in his early 60's, very unassuming, nothing obviously threating to my eyes, however Mooshi took a serious disliking to him for some reason and she let rip. She started to bark, and I mean her serous bark, and she would not let up, no matter how many times I said quiet or its ok she wanted at this guy and she was serious about her business. The foolish man continued to approach me, and asked if she was 'ok'. I mean seriously!! I advised him that it was not a good idea to approach her and to please move away, he didnt listen so he just moved to one side and spoke with my hubby instead. All the while Mooshi is going friggen insane so I had to get up and walk her away. Let me tell you that was not a treat because all the while I am pulling her she wants to go backwards and make hamburger out of this guy. I felt like letting her because he was an idiot but I kept my cool. So I guess what I am trying to say is 'beware'. Our beloved TM's can be really good most of the time, but if they decide not to be there aint a whole heck of a lot you can do other than hang on till the threat passes.