Let's see the baby is 18 months and she became very deperssed within the last year, so she could have experieced post partum deperssion, which is very treatable and life has changed. Your responsibilities have changed and caring for a toddler 24/7 is exhausting and who what to make love when they are so tired from the day that all they want to do is sleep. Welcome to the world of parenthood, but you should both be able to find time just to go out to dinner, a stroll holding hands, a mini vacation (weekend) to rekindle romance and intimacy, but the reality is that working, cooking, cleaning, being a nurse, appointments, time for her personal appearence, etc..is exausting and is definately taking away from intimacy. Time to work out specific dates that will work out for both of you to make time just for the two. Good Luck....p.s. getting angry and using pressure will only cause conflict and for her to back away, so be considerate, help her and ask how can we find time just for us and take it from there. Good Luck.
Antidepressants can erase sexual desire, as can chasing a little child around all day with no help. She could even be suffering from post-partum depression this long after having the baby. I'd ask her to talk to you with a counselor, and just gently ask if she thinks you guys will ever have sex again. Then leave her to talk to the counselor. She probably feels bad about not being interested, and doesn't want to hurt you or insult you, but just doesn't know what to do about it. Try not to get mad, pressuring her won't help, try to be gentle about the question. Good luck.