random weight gain 1.5-2.5 lbs this week

Im am very new to tracking my macros,

175 lbs 5'6
145-155 P
300 C
65-70 F
2300 calories. But i usually only consume about 1900-2100 when i hit my macros.

I recently lost about 5-6 lbs within 4 weeks of tracking, which is great. My strength is increasing slowly. But this week, i've been feeling bloated, and randomly gaining altogether 1.5-2 lbs. Im doing 2hrs of gym session at once in the evening before dinner. I do about 6 miles of cardio a week. Is it because i've been training a little heavier on my bench, back, and legs. Or cause i've increased my water intake by 2 extra cups a day, or was it cause of the Pizza i ate on sunday? Or is 6 days of vigorous workouts and working causing the weight gain?

Like i said im new to tracking macros/myfitnesspal. and my target weight is 170. Im not familiar with the what happens.. ANY information would be helpful. thank you