Losing 70 pounds by next summer/spring!?

cior

So far, I've only lost 20 pounds in 4 months! I am very proud of myself. However I feel like that is going at a slow rate because by next summer (closer to spring), I want to be at my goal weight! I don't think that is unrealistic. I work out every other day, and for some reason, I feel like I should be losing more than that! I eat within my weekly limit, not always the best choices. I have a problem with being over on sodium. I don't think that alone should be holding me back. Also I eat at my BMR. Will I be right on track? Am I losing it too slowly? Is that normal? Any tips and advice would be awesome!!!