The normal advice is to wean around 6 months, but every baby is different. You should really wait for the signs that they are ready: they have good support of their head and can sit well in a highchair. Weaning early isn't good for them, so if she isn't ready at 5 months I would definitely wait. Most babies aren't ready until closer to 6 months, so I don't understand why people are telling you off.
As for BLW vs pureed / mashed, do whatever you are comfortable with and whatever they are interested in. I would suggest going for a combination of both if you aren't comfortable with full on BLW.
I would start with one meal per day, at a time when they are most relaxed, not tired, not too hungry but too full from a bottle. You can give them puree, and also some finger foods to let them feed themselves too. Also, don't worry if they aren't really eating much, that's very normal. Once they are used to the one meal per day, introduce a second meal, once they are good with that, then introduce the third meal. No snacks needed before 12 months usually.
Other good advice is to try to eat with your baby. Sit down together and eat, so they can see you eating and enjoying the good and they will try to copy you.
Weaning is really stressful for first time mums, I know I was super stressed with it with my first and felt like I had no idea what I was doing! Even with watching videos and reading all the advice, it's hard to know what you're doing. Just keep offering them a variety of foods and let them get to know it and taste it, and don't worry about how much they are eating.