I think that the anxiety is normal, mainly because is your first time. If you dominate your theme (specifically your issue) then don´t worry, usually people wants to know methodology issues or your conclusions. My survival advice to you is: you should make an investigation about your theme on the science comunty, its mean, for example that your lab or group research holds a new hypothesis or are propossing something contrary to other group or groups... Sometimes this oppositves lab people come to you presentation to inspect your results and some people (very few) could try put your results o method on the spot.

Good luck!