Family drama

Hey all first time posting, need advice and to get things off my chest.

Me and HTB were supposed to get married this year 3rd April 2021. We are now due to get married (Infact will be getting married 2nd April 2022).
At first before COVID restrictions we were having a wedding of over 200 people (something we both really didn’t want but to please others we said ok) and we wouldn’t have a honeymoon as this would be well over our budget and we don’t want to borrow. so then we decided to scale it down our venue went into liquidation and we decided to buy a marquee and have the wedding at home which would be a lot smaller and something we both wanted.
Our marquee holds 36-40 people. Me and HTB are a blended family him having 3 children 2 of them having partners and our grandchild and me having 2 children one having a partner, between us our children and their partners grandchild and my maid of honour that’s 12 people already. So we decided that between us we have 21 niece and nephews HTB family is very big that we wouldn’t have niece and nephews attend so now our list is ourself children partners grandchild our parents brothers and sister and 3 sets of close friends. Families are going mental my brothers have decided that they aren’t attending if their children aren’t getting my oldest brother came and said he changed his day for me to make room for 1 of my stepchildren at the time she was younger and the invite was for me my htb and my 2 children now at the time my stepdaughter came every 2nd weekend and half the school holidays but I was told if it was our weekend then htb would have to stay at home with her so I decided that if all 3 of our children ( we didn’t make a deal about the older children as they don’t see my family) weren’t getting none of us would go. So now my parents are telling me I’m being selfish and causing problems which I really don’t think is the case I’m not inviting any children at all so I’m not excluding anyone.
Me and my HTB have been together 8 years so you would think they could get past this issue of being a blended family. ( I am the first person in my family to say I’m not happy and walk away from a relationship and family we mortified what are the neighbours going to say to which I replied I actually don’t care me and the children need away from this to be happy)
My HTB has been in my son and daughter life since they were very young son being just 1 their dad now lives away and whilst my daughter calls htb by his name my son calls him dad ( he has done since he has been 2 and seeing other Dads picking up there kids at nursery or at the park etc and their dad only being around them 2-3 times a year we did try stop him but how long do you tell a child off for calling someone dad who does everything that a dad does) my son doesn’t keep very well and spent a lot of time in hospital and had to travel around hospitals in the uk for life saving treatment my htb was at his side with me 24/7 his dad knew and didn’t show face not that I tell my children this because I want them to have a very good healthy relationship with their dad yet any occasion possible the older brother like to “politely remind” my htb he isn’t my sons dad nor will he ever be.
My brothers don’t see why I can’t just wait a few years and save up and have the original big wedding I have explained that we actually didn’t want the big wedding in the first place we would rather a small wedding and again been told we are being selfish.
They also think because HTB has been married before that his family have already seen him get married so I should have more on my side because I haven’t been married before.
Now we are having it at the house people seem to be looking at it as a circus my FIL was complaining about the suit we were hiring and said he wasn’t sitting uncomfortable all day so we told him to wear something more comfortable just dress trousers and a shirt and tie but he isn’t happy about that either he thinks it a joke that we are paying for a bus to bring guest to the house thinks it’s a joke that we are paying for all the food and drink and we should put bring your own bottle on the invites I’m mortified.
I wish I done what we had originally said and that’s ran away and got married and just came back and told everybody however I’m the only daughter so I wanted me and my dad to have that walk me to my future husband down the aisle but it seems everything I’m doing I’m doing wrong
Please give advise am I being selfish?