Semag is absolutely right, your eating is most probably at fault.
However, from a quick skim over your past workouts I've a few comments.
1. No squats - yes I know you work out at home but you're limiting yourself without a power rack, and it's not just squat varations you can do in these, you can also do rack deadlifts, military press, etc. Consider buying one.
2. Your reps are low, 3-5 reps per set seems more of a strength-building routine to me rather than mass-gaining - your bench has gone up like you said (but let's not kid ourselves, 25lbs increase when starting out isn't much). If you were rest-pausing I'd say lower reps was okay but something is wrong here and I'd advise higher reps. 3x8-10 for each set while your poundages are still reasonably low, and don't increase the weight until you at least get 8 per set in reasonable form. (8 reps is just a guideline, but obviously 3-5 ain't helping)
3. You might have gained muscle but lost fat, hence not gaining much weight.
4. You were ill, this might account for some lost weight.
But first of all check out the eating mate. I can tell you already if you're not eating red meat and following a sensible pwo protocol you're already making two basic mistakes.
