Hello
It seems when you try to have sex with your wife, you tend to focus on her age, instead of pleasure. Masturbation has not harmed you in any way so you are absolutely normal. By the way, after marriage, have you penetrated even once? if not, we have to have a different plan ( effective for non consummation of marriage) But is your problem comes and goes by itself, just focus on the pleasure and include touching and rubbing of body parts all over the place with naked body in foreplay. This should be fine
DR SAATIISH JHUNTRRAA