You're just feeling the cycle. For cis-women it's one month, for those of us on HRT it's time between doses. If those doses are daily, then the fluctuation is less and has little noticeable effect. If the time is weeks, then it is more of a fluctuation and more noticeable. It's totally normal. I was using patches which had very little fluctuation as they were twice weekly and continued to give at least some dosing the whole time, and switched to weekly injections and I started to feel more of a fluctuation. The drug does take a while to dissipate into the blood but it's not an even amount the whole week, it's more like a half-life (though not as precise). And it the speed it absorbs will vary slightly based on how deep the needle penetrated the muscle (assuming IM), diet, weight gain or loss, and lots of other factors. For example if you dont get the needle very deep one week you may find a surge in emotion the following day and a significant drop off by the end of the week or even a slight surge in testosterone rage depending of your other meds and transition choices.

I do blood tests every few months and I try to choose a different day of the week each time to get the average. You'll find that the day after your injection will be higher than the day before and half way between it will be somewhere in the middle. Just average them to get your actual levels.

Hormones fluctuate and with them emotions. I personally have enjoyed the change. I prefer feeling things like love and sadness more fully and anger and frustration less so. It's not that they've totally gone away or suddenly appeared, so it's not new, just more or less than I was used to. You'll get used to it just like you got used to quelling the testosterone rage during your first puberty.

That said, see a therapist if it's affecting you a lot. Although women (and thus we) are definitely more permitted to express emotions, socially, cis-women also often have support systems and coping mechanisms in place to help them that they developed during their puberty. Having a good therapist to help you develop those is a real boon.

With valerate, your levels will vary wildly between injections, especially if your injections are spaced 5 days apart, and especially if you were taking oral estradiol 3x/day previously. I was doing valerate once per 5 days for a few months as well and definitely had persistent but irregular periods of extreme tiredness¹ which didn't always seem to be aligned with my injection cycle and mostly went away when I switched to weekly enanthate injections.

I would also note that 3mg of Ev per 5 days is on the low end for monotherapy, it could be that your E is too low near the end of each cycle and you're getting either short bursts of PMS symptoms or constantly toggling T production on and off. That said, without blood work to see what your trough levels are, it's hard to do much more than guesswork. EDIT: skimmed your profile and saw you've had bottom surgery, this whole paragraph is irrelevant I guess :P

¹ no mood swings though - it's been 10 months on HRT now and I'm still waiting for any of those rumored emotional changes...