Hi Pinkjan, I've had bloating and low back pain.
I'm on sequential, Oestrogel 2 pumps and Utrogestan 200mg for 12 nights (I'm 52 and was having very erratic periods sometimes 3 months apart, so that's why I'm on sequential at the moment as I'm not post menopausal yet). I think the bloating is due to the Oestrogen and the back pain only appears when on the Utro part of my cycle.
I've only been on HRT for approaching 4 months, the bloating has only been a problem this month, I'm thinking maybe it's the Oestrogel as occasionally I have tried 2.5 pumps this month as I was having the odd night sweat again and maybe 2.5 is too much for me. The Utrogestan has been making me increasingly tired over the 12 nights I take it, so I've actually tried reducing the Utro to 100mg vaginally this month (in theory you absorb more vaginally and it's meant to help with the tiredness side effect) and I also reduced the Oestrogel to 1 pump last night as I was worried about reducing the Utro so thought I should also reduce the Oestrogel to 'balance' the 100mg Utro (but no idea if that was a good idea) and here I am awake since 3am!
It seems to be trial and error and for me the side effects have settled down the longer I've been on it except for the overwhelming tiredness on the Utro phase, which is why I am experimenting a bit with the dose this month - I was on the verge of stopping altogether.
I did have really bad water retention in my legs this month and I definitely think that was due to taking too much Oestrogel as that was on the Oestrogel only part of my cycle. On the plus side, my night sweats have mostly disappeared and my sleeping was much improved!
So I guess I'm saying, expect side effects but hopefully they should diminish over the first three months. I'm quite a newbie at all of this, but that's my experience so far.