Pat had some very good advice. Assuming you live in warmer region of country then 50 by April is definitely possible.
I might add that you may want to vary your routine. If you are doing 14 now, do a day at 12 and then the next push the max distance up to 15 or 16. But, just as Pat says, don't increase more than 10% total. It is hard on your body yo make drastic increases.
As you you feel more comfortable and the miles start increasing you will be able to push a longer ride ever now and then. That will help get your back side used to longer minutes/hours in the saddle.
Good luck and glad to have you in the Forum!!