hi. 15mgs/remeron can be helpful for low mood and anxiety. it can also be very sedating. weight gain is fairly common with remeron, although I've read that higher doses (30, 45mgs, for instance...) can help some people and the higher doses are less sedating and cause less weight gain.

75mgs/effexor isn't a whole lot. i think that dose is pretty much ssri-action. have you talked to your doctor about trying to increase the effexor, instead of adding another drug? both approaches, of course, have pros and cons. the effexor (full-dose) and remeron combination was/is somewhat popular in "treatment-resistant" depression for a while there...its been nicknamed 'California Rocketfuel," because the combination affects all kinds of neurotransmitters and helps some people who had previously not responded to treatment, or whose treatments had stopped working.

i hope things get better for you soon.