Hello and welcome to Healthcare Magic. Thanks for your query.
From the description of your problems it appears that you are having a problem of
Premature ejaculation. Premature ejaculation can be due to different causes - both psychological causes and medical causes. But in a young person like you, it is more likely due to a psychological cause such as
anxiety. You have already mentioned that you are quite anxious and nervous, and so this could be one of the major reasons for your problem.
To increase the ejaculation time, you can try practicing certain exercises like Kegel's exercises or techniques like the Masters and Johnson technique. Alternatively, there are medication available which can help delay ejaculation time. So, if this problem is very distressing, I would suggest that you
consult a Sexologist for further help and treatment.
Regarding your other question about nightfalls, this is a normal thing which happens and does not cause any sexual or health problems. So, you don't have to worry about this.
Wish you all the best.
Regards,
Dr. Jonas Sundarakumar MBBS., DPM., MRCPsych.(U.K.)
Consultant Psychiatrist