You are doing great. seems quite normal to me - your baby will feed more frequently if always with you both for food and comfort. its up to you how you deal with the comfort feeds if indeed that's what they are. With DS1 I probably let him chill out latched on as i relaxed, watched TV, read etc. DD1 is different as I have too much else to get on with it so its feed and off! So maybe just enjou the long constant feeds if you cant be bothered doing anything else! I think the evenings sound really good in that you have a bit of down time for yourself.
expressing is really hard for some and please dont use that to judge if you have enough milk.
can you go to a BF group of la leche group. sometimes its good just to chat to others, be given tips etc and also to be reassured by the experts on hand.
dont feel guilty about the rice but i do think its too young. also being refined white rice its by default high sugar. you baby is much better getting all the goodness from your milk. one bit wont have done any harm. no guilt please.
Kelly Mom website and DR Jack newman might also have good tips.
I am wary about giving tips as i'm no expert just a mum and cant see you in person - go to a group if you are worried and get weighed as it might put your mind at rest. i was obsessed with weighing DS1 and that helped me alot with my confidence. DD1 has only been weighed when a newborn by MW and now she is 10 months. GP told me off at 8wk check up, i said - "well she is outgrowing her clothes"
You need to put your mind at rest. talking, sharing and getting sensible professional information is the best was to do this.
Well done for getting to 15 weeks... it hopefully will get easier. Nights are always hard