I’m 28 years old got a hb7.5-8 that I’ve been fucking ...sometimes I get really hard and fuck her good but other times my erection is weak or if I get it up it doesn’t last, especially because I’m wearing a condom

I think it might be performance anxiety related...I know now to just focus on myself and that’ll help but I ordered viagra in the meantime...I was planning on taking it but does it cause any dependency? How much should I take?