Hello and welcome to BW forums

Congratulations on your new little boy

Looks like you've done really well to recognise your baby's personality and identify that at times he was becoming over stimulated by his environment and all the people around him. It's important I think to find a suitable compromise or balance between meeting his needs and your own. Clearly you need to get out and have these sociable times with other mums, it's good for your sanity! At the same time LO is becoming overwhelmed and it is a little too much for him. You don't have to keep yourself at home all day though - you can find a balance which works for you both. Going out at roughly the same time each day can really help with sensitive babies they come to expect it and accept it, even more so when they know that other parts of the day are quieter and calmer. Reducing the time you are out might help, or finding a consistent and workable way of baby nodding off for a nap whilst out so that you can stay out longer but without it disturbing or over stimulating him.
When mine was little I remember planning only those baby groups which fell at roughly the same time of day, we had the morning at home, and first long nap at home, then we went out in the afternoon. Some baby groups I arrived late to fit a little better with my DS's going out time and some we left early again to fit with his time - but I didn't stop going. I needed to get out to see other mums and my DS gradually came to love those groups even if he found them very/too stimulating.
Equally when mine was a little older I found ways to help him with the levels of stimulation, either by skipping part of a group (beginning or end), by giving him some say over what we did and when we left, and by teaching and helping him with ways to find peace even in a busy environment (for us this was to turn our backs to the room and look out the window, I would talk quietly to him about what we could see and reassure him that everything was okay...my DS who is now 6 years old can still do this when he is starting to feel overwhelmed. It is a form of self soothing and calming.
Your DS is still very very young and the amount of time he can stay awake is very short. It looks from your EASY that you are trying to keep him up too long. At this age 1hr 15 to 1hr 20 is about all he can manage and this includes time taken to eat and change nappy etc. A time is all the time that is not S time so if he wakes in the morning at 5.30am and this is when you get up for the day then it goes:
WU 5.30
E 5.30
A 1hr 15
S 6.45 - 8.15/8.45 (1.5 to 2hr sleep)
E 8.30 (or 8.45 if he sleeps 2 hrs)
A 1hr 15
S 9.30
and so on
It leave very very little time for interaction or play but as he gets older he will be able to stay awake a little longer.
For E - at this point I would not be trying to wean out any night feeds. If LO is feeding every 3hrs or longer at night that is totally normal. Here on the forums we run with the most recent research on feeding and feel that Tracy would have updated her books and advice accordingly had she still been with us to do so. For such young babies it is advised to feed on demand or every 3hrs and to expect those night feeds, especially for a BF baby - your LO needs to feed at night to stimulate your milk supply. There are also lots of growth spurts at this young age when LO may need additional feeds over night. I know it's really tempting to drop those night feeds and get some sleep but for now I suggest you continue - every 3hrs which is the two NF (night feeds) you have at the moment.
You can introduce a DF (dream feed) before your own bed time, around 10pm ish which can help get a longer stretch before the NF but it's up to you if you prefer to do this or just wait for the NF when baby wakes.
Do not worry about having fed your baby too often (if you did). First off he probably needed it, secondly we don't go for blame and guilt here, you did what you did because you love your baby and wanted to do the right thing - that's all any one can ask isn't it? From here on you can expect to feed at 3hrly interval through the day and possibly more often through illness on hot days and such. We have a great BF board where you can get support and have your questions answered too.
You will eventually get a couple of hours to yourself. He is still very little and still needs you through most of the day and night but as you settle into this routine you will hopefully start to see a consistent 1.5 or 2hr nap at least once per day and can make the most of this Y time.
Your LO will also appreciate the structured routine and together you will learn how to cope with the stimulation levels, how much is enough, what time of day is best for higher and lower stimulation and how to deal with it when there is too much - it's team work, you will help your LO and he will also help you.
I think I have answered your questions. Do let me know if something is not clear or you have more questions. And perhaps you would like to post another EASY in a few days after you have tried out the shorter A time? Let us know how you get on.