No there will be no doubt when she has "took". When she has her ovulation you will notice it. It will literally look like someone has put an air pump to her mid section. She will be bloated like that for about 24 hours.

I am not sure where you are located but you have the best luck in cooler months of the year for a successful breeding.

My female gtp became a insationable eater in the months before becoming pregnant. Be sure to keep the humidity really high and to be dropping your temps a bit slowly of course.

Even if a male mates, the female has to prepare her body by getting into the season or it wont take.

After my female ovulated she refused food and wouldnt even think of eating. Males will not resume eating if they can smell the female so be sure he is far away from her after you are sure she has took.

My male wouldnt feed for a couple of weeks after being separated. Good luck to you. I just hatched my first clutch of gtps on May 22nd and it was amazing!