What's going wrong here?

[respectdue]

I am doing 16:8 5 days a week as I find that if I have breakfast I am much more hungry through the day so skipping breakfast helps me not overeat the rest of the day. On two fasting days a week I do 20:4 (just evening meal).
I have been doing this for a month now and I lost 8lbs in the first couple of weeks, the third week was my period so the scales don't mean anything, but a week later (still sticking to 16:8 & 20:4) I have gained 1 lb back!
I eat carefully all week and def stay within my TDEE of 1950 cals but have been away for the last few weekends and had lots to eat and drink (although still 16:8)
I have reduced my overall calorie intake quite significantly (skipping 7 breakfasts and two lunches a week= c. 4500 cals) and in between eaten substantial but careful meals (except on weekends) so I can't think that my body would go into starvation mode.
What do I need to do?

is that TDEE sedentary or have you allowed for activity?

have you dropped your TDEE down with weight loss?

are you drinking enough water at the start of every meal?

how many calories in the 20:4 meal ?

The TDEE is 1977, activity level lightly active (I go to power yoga twice a week and my job keeps me moving, I am also a fiend with keeping the house tidy).
However, this week I have hurt my knee so missed two yoga sessions and sat around a lot more doing RICE protocol on my knee. I hadn't really taken that into account.

I do drink absolutely loads of herbal tea (10 big mugs a day) so no probs on the fluid front, but I don't drink it at the start of my meals, should I?
On a 20:4 day I guess my meal would be about 600 cals but probably I need to be stricter there and actually stick to the 500 (I was hoping that because I was doing 16:8 the following day, meaning that the evening meal was the only food i was having within that 38 hour window it wouldn't matter if I went over a bit).
I also stayed with family over the weekend for a party where I did have cake/wine/party food/sunday lunch etc etc so no calorie control there other than still sticking to 16:8.

I think you've answered your own question there - less activity and more eating doesn't = weight loss! But you have maintained, and that's important. 1lb doesn't count as a gain - that's the weight of your big cup of herbal tea, and the amount in your system digesting weighs far more!

However, it is important to bear in mind that weight loss doesn't occur as a smooth downward curve - most of us tend to bounce around a weight for a while (ie up and down by a couple of pounds either way) then drop a few pounds suddenly. You haven't said what your BMI is or how much you need to lose so if you are close to target then it will be slower.

I don't think you need to be stricter on fast days necessarily but drop a few calories over the week to allow for less activity.

Having a day off each week (ie eating more than your tdee) can help believe it or not - lets your body know that there are occasional feast days and not to worry too much on the fast days, and therefore not cling on to every ounce of stored fat .